French President Emmanuel Macron is set to pressure Britain on Tuesday to contribute more to dealing with migrants trying to cross the Channel from Calais, while defending his own under-fire policy to stem new entries into France.

The 40-year-old centrist travelled to the northern French port ahead of a summit with British Prime Minister Theresa May on Thursday and at a critical time for his efforts to toughen up France's migration policies.

At stake with Britain is a 2003 agreement which effectively moved the UK border onto French territory, meaning the area around Calais has become a bottleneck for migrants hoping to cross to England.

Interior Minister Gerard Collomb reiterated Tuesday that his government would ask Britain to take in more refugees from northern France and increase its funding.

"It's in their interests that things go well," Collomb told France 2 television ahead of Thursday's meeting between Macron and May in London.

Referring to the importance of Calais for the British economy, which faces uncertainty ahead of Brexit, Collomb added that "a quarter of their trade transits through Calais."

Police in the port city routinely break up makeshift camps of migrants hoping to stow away on trucks crossing to Britain, a favoured destination for Afghans and east Africans.

As a candidate ahead of his election in May, Macron consistently said that he intended to renegotiate the 2003 border agreement with Britain, known as the Le Touquet accord.

Allies attack
The French president will also use Tuesday's visit to defend his government's uncompromising attitude ahead of a new immigration law that will seek to clamp down on illegal arrivals while opening up legal avenues for asylum seekers.

France received a record 100,000 asylum claims last year, making it one of Europe's top destinations.

Macron has promised to speed up waiting times for asylum applications while also stepping up expulsions of economic migrants -- an approach he touts as mixing "humanity" and "efficiency".

The biggest group of applicants for asylum in 2017 consisted of Albanians, almost all of whom will have their requests turned down because the southeast European country is considered safe.

The migrant issue is set to become one of Macron's most tricky political tests because of splits in his newly formed Republic On The Move (LREM) party and public criticism from some of his closest allies.

His former senior aide Jean Pisani-Ferry penned a hard-hitting open letter along with several centre-left trade union and think-tank chiefs claiming Macron risked betraying his image as a humanist.

Writing in Le Monde newspaper, they urged him to "live up to our ideals, to use your own words" and put an end to efforts that seek to dissuade asylum seekers from coming to France in the first place.

Anger in Calais
Two NGOs on the frontline in Calais have refused an invitation to meet Macron on Tuesday due to repressive measures used by French police to stop migrants setting up camps there.

Francois Guennoc of the Auberge des Migrants charity said he did not want to act "merely as an alibi for a strategy that is already well established".

Auberge des Migrants and another Catholic group have filed a criminal complaint over security forces allegedly destroying the belongings of migrants in the area.

Despite Macron's statement in July that he wanted "no more migrants in the streets, in the woods", hundreds of people are still camped out in the area around the port.

In late 2016, the former Socialist government demolished the Jungle, a squalid makeshift camp in Calais, and moved its more than 7,000 occupants to shelters nationwide.

Natacha Bouchart, the right-wing mayor of Calais, told BFM television on Monday that the local population was "tired" of the situation and expected a lot from the president's visit.