French authorities have been accused of "throwing their teddy out the pram" after a UK boat was detained in a worsening row over post-Brexit fishing rights.

Jon Nichols, chairman of the Thanet Fisherman's Association, says the incident is another example of "childish behaviour" from our continental neighbours.

Downing Street has labelled the drama off the coast of Le Havre "disappointing" and says it will seek a resolution.

The scallop vessel Cornelis was ordered to divert to the port of Le Havre after the French authorities said it was fishing in French waters without a licence.

The French said that another British trawler had been fined for obstruction after refusing to allow police to board to carry out checks.

The incidents came amid anger in France after the UK and Jersey turned down applications from dozens of French boats to fish in their waters, in what Paris said was a breach of Britain’s post-Brexit trade deal with the EU.

Mr Nichols said: "They've thrown their teddy out the pram as always.

"It's just childish behaviour as usual.

"Our government has to be as equally strong as the French. We need to put our foot down and we do not need to be blackmailed by other nations.

"It's difficult times."

French ministers have warned they will block British boats from some its ports and tighten checks on vessels travelling between France and the UK if the issue is not resolved by next Tuesday.

Environment Secretary George Eustice says the threats appeared to breach international law and warned the UK would respond in an “appropriate and calibrated” manner if they were carried out.

'It is rather puerile sabre-rattling.'

South Thanet MP Craig Mackinlay delivered a withering denunciation of the threats made by the French authorities.

The MP accused France of engaging in puerile sabre rattling and said the UK was being wrongly accused of breaching post-Brexit arrangements.

“The UK gets accused of breaking the Trade and Co-operation Arrangement [TCA] and here we have the French threatening this and that...

"It is rather puerile sabre-rattling. The TCA is very clear about the French fishing in UK waters. My understanding is that the French have not been able to show their ‘grandfather’ rights from the past.

"It is very clear in the agreement that was signed. The UK has been very accommodating.

"This is tit for tat stupidity probably designed by Macron for his re-election campaign to stand up to perfidious Albion.”

However, he said that he did not welcome the spat and wanted a “good working relationship” with France and for both to be friendly trading partners.

The TCA agreement governs the relationship between the EU and the UK after Brexit.

It provides for free trade in goods and limited mutual market access in services, as well as for cooperation mechanisms in a range of policy areas – including fishing.

Failed South Thanet candidate Nigel Farage tweeted the British should take firm action and impound a French vessel next time in retaliation.

Meanwhile, Downing Street says it will continuing to seek talks with the French government and the European Commission to resolve the dispute over fishing licences.

A spokesman said: “We are monitoring this situation very carefully. We have relayed our concerns to the commission and the French government.

“We think the threats outlined yesterday evening were disappointing, were disproportionate and were simply not what we expect from a close ally and partner.

“I can’t at this moment set out exactly what our response might be. It will be appropriate, it will be calibrated.”

Earlier, France’s Europe minister Clement Beaune told French TV news channel CNews: “We have been extremely patient… our fishermen have been extremely responsible.

“And so, from November 2, it’s over: we will engage in dialogue if the British want to, but we are taking retaliatory measures.”

“Now we need to speak the language of force because, unfortunately, that seems to be the only thing this British Government understands.”

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