French President Emmanuel Macron hit out at British Prime Boris Johnson on Friday over a tweeted letter, accusing him of being "not serious" after 27 migrants died crossing the Channel.

Johnson sparked fury in France after writing a private letter to Macron on Thursday evening proposing five ways to stop migrants crossing from France to Britain, then publishing it in full on his Twitter account.

"I am surprised by methods when they are not serious. One leader does not communicate with another on these questions on Twitter, by public letter... No, No," Macron told a press conference in Rome.

Relations between the two neighbours were already seen as their most tense in decades following a series of disputes over Brexit, but the personal criticism of Johnson represents a further turn for the worse.

French fishermen also began a temporary blockade of cross-Channel ferries and trains on Friday to protest against Britain's new licensing process which they see as obstructing their work.

Analysts say the lack of trust and goodwill between Paris and London will make it more difficult to mount a coordinated response to the growing numbers of people seeking to cross the narrow but treacherous waterway separating the countries.

In response to Johnson's letter, French Interior Minister Gerald Darmanin cancelled planned talks with his British counterpart Priti Patel on Sunday, informing her that she was no longer invited to a meeting with other European ministers.

In a message seen by AFP, Darmanin told Patel the letter was a "disappointment" and "making it public made it even worse."

"We consider the British Prime Minister's public letter to be unacceptable and contrary to the discussions we had with our counterparts," a French source close to Darmanin told AFP, asking not to be named.

Johnson wrote that he had "long been profoundly concerned" about a tragedy in the Channel and "such a catastrophe has now happened" following an accident on Wednesday in which 27 people drowned when their inflatable boat sank.

As well as reiterating a request to send British security forces to France for joint patrols -- a sensitive issue for Macron -- he also asked France to immediately start taking back all migrants who land in England.

A spokesman for Johnson said he had no regrets about making the letter public, saying the public "would rightly want to know what we are looking at in terms of trying to solve this problem".

Speaking to the BFM TV channel, government spokesman Gabriel Attal called the letter "threadbare in its substance and completely inappropriate in its style".

The idea of sending back migrants to France "is obviously not what we need to resolve this problem", he added.

Britain's Prime Minister Boris Johnson has again sparked anger in Paris with after posting a letter to President Emmanuel Macron on Twitter Britain's Prime Minister Boris Johnson has again sparked anger in Paris with after posting a letter to President Emmanuel Macron on Twitter Photo: POOL via AFP / Christopher Furlong

"You could ask now whether Boris Johnson regrets leaving Europe because as soon as there's a problem he considers it Europe's job to solve it," he said, targeting Johnson's role as a key architect of Brexit.

Macron said Sunday's meeting in the port of Calais with German, Dutch and Belgian interior ministers, as well as the European Commission, would go ahead without the UK.

Seventeen men, seven women and three minors died on Wednesday when their inflatable lost air and took on water off Calais, dramatically escalating a crisis that had already seen around 25,700 people cross the busy shipping channel this year in small boats.

Five suspected traffickers accused of being directly linked to the doomed crossing have been arrested.

A French fisherman who raised the alarm about the accident said he is having nightmares having witnessed "so many dead like that next to us."

"As soon as you close your eyes, you see the bodies again," Karl Maquinghen, whose boat is based in Boulogne-sur-Mer on the French coast, told AFP.

"We were even afraid to haul up the nets -- for fear that there would be someone else inside there."

The new row has added to a series of post-Brexit arguments between Britain and France from fishing rights to trade between the EU and the British province of Northern Ireland.

French fishermen used their boats to blockade Channel ferries in the ports of Calais and Ouistreham and also parked vans in front of the freight entrance to the Channel Tunnel, the rail link between the countries.

"We want our licences back," read an English-language banner brandished on one of the boats, the Marmouset II, in Calais.

Paris says more than 150 French boats have been rejected after applying for licences to fish in waters around Britain and the Channel Islands, self-governing islands that depend on the UK for defence.

Under a deal agreed by Britain and the EU late last year, European fishing vessels can continue to ply UK waters after Brexit if they apply for new licences and can prove they operated there in the past.

Britain denies obstructing French boats and says many have been rejected because they were unable to provide proof of their previous work.