French officials have warned that it will bar UK fishing boats from some ports and tighten customs checks on lorries entering the country with British goods from Tuesday unless more licences for small boats to fish in British waters are granted.

       The row has threatened to boil over as Brexit minister Lord Frost accused France of a "pattern" of behaviour against Britain, with ministers in Paris having previously suggested they may restrict energy supplies to the UK and Jersey because of the disagreement.

       The Prime Minister met with the European Union's top official, Ursula von der Leyen, in person while in Rome for the G20 summit to express his "concern" over France's behaviour.

       One UK Government source said after the meeting on Saturday: “The EU needs to do something here because if France goes ahead it will put the whole EU in breach.”

       A letter from French prime minister Jean Castex to European Commission president Ms von der Leyen, in which he said the UK should be shown "it causes more damage to leave the EU than to stay in", also sparked fury in London.

       The Sunday Telegraph quoted a senior Government source who said Mr Castex's letter "definitely raises a question" of whether the EU was "acting in good faith" around the talks on Northern Ireland.

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