Fishing must be disentangled from any Brexit free trade agreement with the EU, MPs will tell the Prime Minister at a Downing Street summit.

Conservative MP David Duguid (Banff and Buchan) said he would tell Theresa May the EU must be rebuffed in its attempts to tie fishing quotas to a free trade deal – or she risks being seen to have betrayed fishermen.

Mr Duguid said the European Commission’s starting point was to keep the same access to UK fish as a condition of getting a free trade agreement and, although negotiators had softened, they must dump the demand entirely.

He said: “The point is there is no precedent for this anywhere else in the world where a free trade agreement would be tied to natural resources.

“I know from talking to representatives of the EU fisheries sector their demands have lessened as matters have progressed.

“However, it needs to be about zero – anything more than that will be seen as a betrayal.”

Barrie Deas, National Federation of Fishermen’s Organisations (NFFO) chief executive, said he believed the “parliamentary arithmetic” and the symbolism of the totemic industry was on fishermen’s side.

He said: “I think it’s very clear fishing is high on the agenda, partly because of the parliamentary arithmetic and also because fishing is symbolic of Brexit.

“The general public may not know what Brexit means in its entirety for some years but we will know on day one whether fishing has got a good deal or a bad deal.

“If we are sold out like we were going into the EU in 1973 there would be a political cost to that – if we are tied into the status quo that seems like betrayal.”

However, Scottish Fishermen’s Federation chief executive Bertie Armstrong said he was quietly confident fishermen would land the deal they wanted, whatever the outcome of Brexit.

“The key to all this is backbone,” he said.

“At the party conference Mrs May mentioned fishing twice in her keynote speech – it has been a while since any prime minister did that, so we are encouraged but not complacent.

“The right thing to do with fishing is so obvious that it will happen no matter whether we end up with Chequers, Norway, Canada or a no deal Brexit.”