EDINBURGH (Reuters) - Producers of Scottish salmon, Britain’s biggest food export, are seeking reassurance that the Brexit deal will not link fishing in British waters by European Union boats with the supply of all British seafood products to EU markets.

Julie Hesketh-Laird, chief executive of the Scottish Salmon Producers Organization, said “serious questions” were raised by Britain’s draft agreement with Brussels to exit the European Union published last week, and for which Prime Minister Theresa May is struggling to get political backing at home.

British salmon is a 1-billion-pound industry and all of it is farmed in Scotland. It is not subject to the EU’s Common Fisheries Policy which sets quotas for access for caught white fish at sea. But the draft opens the potential for this to change, Hesketh-Laird said on Friday.

“By coupling aquaculture with future catch fish quotas, this document raises the prospect of tariffs being imposed on exports of farmed fish if there is no agreement on North Sea white fish quotas.

“It also raises the prospect of border checks for fresh salmon exiting the UK bound for our biggest export market – the EU,” she said.

While she recognized this would only happen if the proposed deal was implemented unamended and if there was no mutually acceptable deal on fisheries, it was, in her view a risk.

“There must be no linkage between access for EU vessels to UK waters and the tariff-free entry of seafood products to EU markets,” she said.

Her words chime with those of some Scottish lawmakers in May’s own Conservative party, who are looking for a “cast-iron guarantee” that any fisheries agreement will not link access to British fishing waters with single market access.

May sought to allay those fears in parliament on Thursday, saying: “The fisheries agreement is not something we will be trading off against any other priorities”.