The UK nuclear industry has issued its strongest warning yet to ministers on the problems it faces if the government is unable to strike new international atomic power deals during Brexit talks.

Failure to put in place alternative arrangements to replace the existing European nuclear treaty, Euratom, which the UK is quitting as part of the article 50 process, would have a “dramatic impact” on Hinkley Point C and other new power stations around the country, the industry said.

Ministers must avoid a “cliff edge” when the UK exits Euratom or face “major disruption to business across the whole nuclear fuel cycle”, the Nuclear Industry Association will warn the government on Wednesday.

The stark briefing to officials, seen by the Guardian, comes just a day after MPs said the continued operations of the UK nuclear industry were at risk from exiting the Euratom treaty. A Lords committee on Tuesday also said the UK risked losing access to markets and skills when leaving Euratom.

Tom Greatrex, the chief executive of the NIA, said: “We’ve had today two select committee reports that have both touched on this. The industry has been and is clear to government we are ready to do what we can – but it needs the government to get on with this and engage now, regardless of all the other issues they have to deal with.”

Theresa May’s decision to call a general election had made matters worse, he added, because it had squeezed the time available to establish alternatives to the treaty.

Euratom was first signed in 1957 by Belgium, France, Germany, Italy, Luxembourg and the Netherlands, and covers nuclear power station inspections, trade of materials and research.

The UK’s departure will mean the government needs to agree a new inspections regime with the International Atomic Energy Agency to replace Euratom inspectors.

“If the UK has not replaced the Euratom safeguards regime with its own system by the time it left Euratom, normal business could be disrupted right across the nuclear industry,” the NIA paper said. Falling back on World Trade Organisation standards would risk putting the UK in breach of its obligations in international nuclear law, the organisation added.

Nuclear cooperation agreements (NCAs) would also need to be put in place with key nuclear countries outside the EU, including the US, Japan and Australia, because the UK’s agreements with those governments are currently based on its membership of Euratom.

The report said: “Leaving the Euratom treaty without alternative arrangements in place would have a dramatic impact on the nuclear industry including the UK’s new build plans, existing operations and the waste and decommissioning sector which all depend, to some extent, on cooperation with nuclear states.”

Greatrex said that matters were complicated by the fact that things had to be done in sequence, rather than in parallel. The new safeguards and inspection regime needed to be in place before the NCAs were struck, for example.

Nuclear experts said that despite the dire warnings, the industry was not exaggerating the risks.

Dame Sue Ion, honorary president of the Nuclear Skills Academy and former chair of the Nuclear Innovation Research Advisory Board, said: “It’s absolutely real [the impact if alternatives are not in place]. It literally does mean you cannot move material or IP [intellectual property] or services or components or medical isotopes.”

She was echoed by Rupert Cowen, a senior nuclear energy lawyer at Prospect Law. “I don’t think they’re overstating the case,” he told the Guardian. Cowen was critical of officials in government who he called “ignorant” of the impact of leaving Euratom and who “think it’ll be alright on the night. It won’t.”

The NIA urged the government to give “strong consideration” to remaining a member of Euratom if it had not thrashed out new deals and arrangements by the end of the two-year window triggered by article 50.

A government spokesperson said: “The UK has a world-leading nuclear industry and the government is working to ensure effective arrangements remain in place for nuclear co-operation with both Europe and the rest of the world. We will remain absolutely committed to the highest standards of nuclear safety, safeguards and support for the industry.”