The Channel migrant crisis could get even worse as France plunges into economic chaos, Sir Keir Starmer has been warned.
French interior minister Bruno Retailleau said his department could face a funding shortfall of £624million (€751million) next year.
He said this “means problems paying the police” who patrol the beaches in northern France.
France’s minority government is on the brink of collapse after Brexit nemesis Michel Barnier used special powers to force through his budget without a vote in parliament.
No-confidence votes are now set to take place on Wednesday.
Britain relies on the French Gendarmes and Police Nationale to stop migrants from boarding boats bound for Britain.
The French interior minister said: “If we do not have a text, including a budget text, for the Ministry of the Interior, it is €751million less if we renew the 2024 budget for 2025.
“This means problems paying the police, no new gendarmeries, no new police stations.”
Shadow Home Secretary Chris Philp told the Daily Express: “Labour’s lack of a plan to control the border is causing chaos.
“They never should have scrapped the only deterrent stopping the influx of small boat crossings – now we face a fresh migrant crisis.”
Robert Bates, research director at the Centre for Migration Control, told the Daily Express: “The only real contribution the French have made to the Channel crisis is to escort migrant boats into British waters and then wash their hands of the problem.
“We have been paying them hundreds of millions to effectively exacerbate the problem.
“This planned cut to their policing budget will no doubt see them demand more money from the British Government, knowing full well that the Labour Party will give them what they want.
“This would kibosh any effort to smash the gangs on the continent and leave us doing all the heavy lifting.
“Working with Europe on this issue is creating more problems than solutions. A unilateral commitment to detain and deport illegal migrants is the only way to properly end illegal migration.
“On this issue, the French are not our friends, and simply see us as an easy revenue stream. Strengthening our borders does not require the generosity of others to make it work.”
Reform UK deputy leader Richard Tice said: “It’s quite clear that far from smashing the gangs, it’s only going to get worse under Labour.
“Labour needs to start putting British people first and not allowing our borders to be at the whim of French politics.
“Reform UK is clear, our plan is to pick up and return the boats to France as allowed under the UN Convention of Law at Sea. This will stop boats within weeks but requires leadership not cowardice.”
Britain last year agreed to pay France more than £500million to bolster law enforcement operations to stop small boats from leaving France.
But more than 20,000 migrants have arrived in the UK after crossing the English Channel since Sir Keir Starmer became Prime Minister, Home Office data has confirmed.
Overall, 33,684 people have crossed the Channel this year.
Mr Retailleau told French broadcaster TF1: “We are in a critical moment for France.
“We risk chaos, we risk a financial crisis,” he said, comparing it to the “public debt crisis in Greece in 2008”.
Mr Retailleau continued: “It is not those who are rich who are the first to be impacted, it is the most modest, the most fragile.
“And during this time we have a part of the political class playing Russian roulette. Let’s wake up and prevent what seems inevitable – chaos.”
On Friday, the French interior minister blamed Brexit for “destroying immigration cooperation” between the two countries, saying that France was ready for a “showdown” on border security.
He added: “I hope it won’t come to that, but we have to change this relationship.”
Mr Retailleau called for a more comprehensive deal between Britain and the EU ahead of a meeting with Home Secretary Yvette Cooper on December 9.
Furious opposition parties said they would back a no-confidence motion to oust the former Brexit negotiator in a vote that could take place as early as Wednesday.
Mr Barnier opted to push through controversial reforms to social security by invoking presidential decree after failing to win enough support for the measures.
Two motions of no-confidence will be debated in the National Assembly in Paris from 4pm on Wednesday, with a vote at around 7pm.
This means that Mr Barnier could be out of power by Thursday – the three-month anniversary of President Emmanuel Macron appointing him prime minister.
No French government has been forced out by such a vote since 1962 and it would make Mr Barnier, 73, the shortest-serving prime minister in the history of the Fifth Republic.
Mr Barnier, the former EU Brexit negotiator, is Mr Macron’s fifth prime minister in seven years.
