The UK Government has opened a 12-week consultation on new legislation for critical undersea infrastructure, proposing tougher criminal penalties and new security powers as Britain expands the subsea cables, electricity links and offshore infrastructure on which its energy and communications systems increasingly depend.
The proposals would modernise a legal framework whose principal offence for damaging subsea communications cables dates from the Submarine Telegraph Act 1885. The Government says the existing law still refers to telegraphic communications and makes only limited provision for energy infrastructure, despite subsea telecoms cables now carrying about 99% of the UK's international data traffic.
Energy infrastructure is also directly within the scope of the proposed criminal-law reforms. Government figures say undersea pipelines provide 74% of the UK's gas supply, while electricity cables connect Britain with European markets and an expanding offshore energy system.
The Critical Undersea Infrastructure Security and Resilience White Paper, published on 22 October, contains 72 consultation questions and will inform future legislation. The measures are therefore proposals rather than rules already applying to projects under construction.
A UK coastal cable landfall construction site illustrating the civil engineering, underground cable routes and electrical infrastructure connecting subsea energy networks to the mainland. Illustration: London Construction Magazine.
What the Proposed Law Would Change
The Government proposes a new criminal regime covering harmful conduct against critical telecoms and energy infrastructure beneath the sea. Intentional damage could attract prison sentences of up to 14 years, while the wider package would allow stronger penalties, including unlimited fines, for conduct that intentionally, recklessly or negligently damages protected infrastructure.
The regulatory proposals are more targeted than the headline coverage may suggest. New statutory security and resilience duties would apply principally to providers of subsea telecoms cable infrastructure and services, requiring them to identify and manage risks to their networks. The Government is also proposing a national-security direction power allowing the Secretary of State, where necessary and proportionate, to require action from subsea telecoms infrastructure providers and organisations providing cable repair capability.
A further regime would cover fibre-optic sensing technologies installed on subsea cables. These systems can use existing fibre to detect activity around cables and other offshore assets, but the Government considers that their deployment also requires controls where sensitive information could create national-security risks.
For the construction and engineering sector, that distinction is important. The White Paper does not impose a new blanket design standard on every electricity interconnector, offshore wind export cable or pipeline. Its direct statutory resilience proposals currently focus heavily on telecoms. However, energy infrastructure is included within the proposed criminal protections, while the policy direction places greater emphasis on the physical security, monitoring, maintenance and repairability of infrastructure built on and beneath the seabed.
The UK Is Building a Much Larger Subsea Construction Pipeline
The proposals arrive while subsea electricity construction is moving into a period of unusually high activity. LCM's review of where UK construction investment is moving into 2027 identified electricity transmission as one of the strongest long-duration markets, with workload extending through converter stations, cable systems, substations, civils, landfalls and specialist electrical installation.
National Grid and SP Energy Networks are developing a series of large high-voltage direct-current links between Scotland and England. Eastern Green Link 3 alone involves a 690km HVDC connection, including approximately 580km offshore, with contracts worth nearly £3bn awarded to NKT and Hitachi Energy for the cable system and converter stations.
Eastern Green Link 4 has a separate £2bn cable contract with Prysmian, covering more than 640km of cable, including approximately 530km subsea. National Grid and SP Energy Networks later confirmed around £3bn of major supply-chain contracts for the wider EGL4 programme after Siemens Energy was selected for the converter stations.
Further north, physical construction is already under way on SSEN Transmission's Spittal to Peterhead project. The 2GW scheme will provide a 166km HVDC subsea link between Caithness and Aberdeenshire. NKT is the principal cable contractor, with local contractors John Gunn and Sons and Nicol of Skene involved in onshore works. At Rattray Head, construction includes a 1.7km horizontal directional drill forming the cable landfall connection beneath the coastline.
SSEN Transmission and Nexans are also progressing the Orkney Link, which combines a 53km subsea cable with approximately 14km of underground cable across Orkney and new substation infrastructure. The broader offshore workload sits alongside the wind-sector pipeline examined in LCM's coverage of The Crown Estate's offshore wind and infrastructure programme, where cable routes, grid connections, ports and marine logistics form part of the construction market around offshore generation.
Repair Capability Becomes Part of Infrastructure Resilience
Installation is only one side of subsea infrastructure delivery. Once a cable is operational, access to specialist vessels, replacement cable, marine crews and suitable weather windows determines how quickly a physical fault can be located and repaired.
The Government said earlier this year that a repair vessel typically reaches a damaged UK telecoms cable within around eight days. It has also been carrying out market engagement on maintaining a UK-based, UK-flagged sovereign cable-repair capability, with a decision expected before the end of 2026.
The practical importance of repair capacity was visible in Orkney this year when damage to a subsea telecommunications cable disrupted broadband, mobile connectivity, card payments and some council services across the North Isles. Orkney Islands Council reported in April that the repair vessel had reached the damaged cable but required five suitable weather days to complete the work.
Bringing repair capability within a proposed national-security direction framework potentially gives the Government a more direct role where the availability or deployment of specialist repair resources becomes a national resilience issue. Exactly what that would mean for contractors, vessel operators and maintenance providers will depend on the legislation eventually brought forward after consultation.
Security Could Become a Bigger Part of Subsea Procurement
For future infrastructure procurement, the direction of travel is towards security and resilience being considered alongside capacity, cost and programme. Cable route design, landing infrastructure, monitoring, access to repair capacity and the ability to recover from physical damage are already engineering considerations; stronger statutory duties could give some of those issues greater regulatory weight in the telecoms sector.
Cable landing stations are also receiving closer attention. Earlier in 2026 the Government commissioned work on protective-security guidance for UK landing-station operators, describing the facilities as the physical interface between undersea cables and terrestrial infrastructure and identifying them as strategically important assets exposed to physical and cyber threats.
The construction opportunity should not be overstated at this stage. The White Paper does not announce a new capital programme or award new security, cable or marine engineering contracts. Its immediate effect is regulatory consultation. The longer-term significance for contractors will depend on whether final legislation produces additional requirements for monitoring infrastructure, protected landing facilities, maintenance readiness, sensing systems or domestic repair capacity.
The consultation is now open for 12 weeks, with the Government specifically seeking responses from infrastructure owners and operators, maritime organisations, fishing interests and providers of subsea fibre-optic sensing technology. Those responses will shape the legislation that follows, at a time when the physical network the law is intended to protect is becoming larger, more valuable and more construction-intensive.
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