Protesters spent the night at a checkpoint where lorries carrying fish from Britain into the northern French ports of Dunkirk and Calais are subject to hygiene checks, now that the UK has left the European Union.

The fishermen set fire to pallets and tyres to stay warm at the Boulogne-sur-Mer checkpoint, in France's busiest fishing hub.

Many trucks from the UK changed routes after hearing of the planned action.

British-flagged ships operated by Dutch companies, which often unload fish caught in UK waters at French ports, had also changed course towards Belgium, the harbour master's office told AFP.

A second group of protesters took up positions for a protest at the Boulogne fish market.

'This night of action is a warning shot,' said Olivier Lepretre, head of the regional fishing committee.

'If nothing happens at the European level, we will shift up a gear.'

Lepretre said UK authorities had only granted licences to 22 out of the 120 boats seeking permission to fish between six and 12 nautical miles from the British coast.