Boris Johnson was on Thursday accused of “betraying” the UK fishing industry, after the “sea of opportunity” promised by ministers following Brexit turned into massive disruption to the sector.

The prime minister has suggested the industry could be compensated for losses caused by huge bureaucratic delays facing seafood exporters since the end of the Brexit transition period on December 31.

But George Eustice, cabinet minister for fishing, was unable to give details of any compensation scheme in the House of Commons on Thursday and claimed the disruption only amounted to “teething problems”.

Anger among Scottish fishing communities intensified when Scottish minister David Duguid, asked by the BBC when seafood exports would run smoothly again, replied: “How long is a piece of string?”

There has also been criticism of UK fisheries minister Victoria Prentis, who admitted she did not immediately read the details of the Christmas Eve fishing deal agreed by Boris Johnson as part of an EU trade agreement because she was organising a nativity event.

Mr Eustice faced questions from MPs representing fishing communities from across party lines, including some Conservatives, over what the government would do to ease the problem.

He told MPs: “Once people get used to the paperwork goods will flow normally.” He said the government remained “open to compensation for sectors that may have been affected through no fault of their own”.

Mr Eustice said the EU trade deal would give British boats greater access to fish in UK waters. Previously Michael Gove, Cabinet Office minister, claimed Brexit would offer “a sea of opportunity” to the sector.

But Luke Pollard, Labour’s spokesman on fishing, and Deidre Brock, his Scottish National party counterpart, both accused the government of “betraying” the fishing industry. “It’s not teething issues, it’s chaos,” Ms Brock said.

Industry trade body Scottish Seafood said computer failures and complex new paperwork had rendered exports to the EU impossible for some companies, leading to crashing fish prices and boats being tied up in harbours.

Industry groups have repeatedly appealed to the UK government to seek a six-month EU grace period for implementation of post-Brexit paperwork, saying failure to do so could leave some exporters unable to survive.

“Trying to navigate the system we have at the moment is like pushing water uphill, and it is not improving,” Donna Fordyce, Seafood Scotland chief executive, said on Thursday. “At the heart of it, the UK system needs fixing. This cannot be done while it is live.”

But Mr Duguid waved aside the call for a grace period of the sort the UK has already granted imports from the EU, saying he was confident export problems could be resolved.

“Grace period or no grace period, you are going to have the same problems,” he told the BBC. “I would rather focus on fixing the problems as they come up.”

DFDS, a leading shipper of Scottish seafood to the EU, this week extended its suspension of services to smaller exporters that send their product to France on lorries together with those of other producers, a practice known as groupage.

DFDS also warned that if groupage services were resumed as now planned on January 18, shipments would take two days to reach the vital market of Boulogne-sur-Mer in France, rather than the next-day service offered before the end of the Brexit transition.

Such delays could have major implications for the value of premium live and fresh seafood to EU buyers. The government has set up a £100m fund to develop the fishing industry post-Brexit.

The chaos over fisheries is politically dangerous for the Conservatives, since it plays into the anti-Brexit message of Nicola Sturgeon, Scotland’s first minister and SNP leader, ahead of this year’s elections for the Scottish parliament.

Several Tory MPs represent Scottish fishing seats at Westminster; the return of British sovereignty over UK fishing grounds was supposed to be one of the big benefits of Brexit.

Jacob Rees-Mogg, leader of the House of Commons, said on Thursday the government was moving as quickly as it could to tackle the border disruption, quipping: “The key is that we’ve got our fish back! They’re now British fish and they are better and happier for it.”