Plans to strengthen fisheries protection operations are unlikely to be ready by the time Britain leaves the EU, according to a new report.

The Treasury is refusing to release money for new ships, aircraft and personnel to staff them until Defra provided a full business case, the National Audit Office said.

This was due in July, but an outline case was only submitted in August, estimating that it would take eight months to introduce measures to boost “control and enforcement” in English waters, meaning they would not be ready by March.

The fishing industry is worth £682 million to UK GDP, the report said.

Currently, the UK uses a “risk-based intelligence-led approach” which utilises a system in which EU nations share data.

Defra wants to boost this with more sea and airborne assets, but has “not yet fully developed its plans to do this”, the NAO said.

The enforcement is carried out by carried out by the Marine Management Organisation, a government agency, for Defra.

The report, released by the NAO on Wednesday, said: “Defra’s contingency plan is to continue with the current level of surveillance and manage the associated risk of lower capacity.

“The risk will be heightened if the UK loses access to EU intelligence and the mutual support that its current approach relies on.”

It added: “In a no-deal scenario, Defra may have to scale up its capacity over time, but is confident that it will be able to manage the risk of any disruption in the interim.”

A Defra spokesman said: “Since the report was written, we have continued to reprioritise our resources, expanded our workforce and made further progress on our extensive programme of work focused on preparing for a range of Brexit scenarios.

“Our work will mean that environmental, welfare, and biosecurity standards will continue to be met in a way that supports trade and the smooth flow of goods.”