French President Emmanuel Macron has said the UK and France "will deliver" on stopping small boat crossings, ahead of negotiations with Sir Keir Starmer this week.
Downing Street is hoping to finalise a deal on border enforcement during Macron's three-day state visit, the first by a French president since 2008.
The talks are expected to focus on new powers for French police to intercept boats in shallow waters and a "one in, one out" migrant returns deal.
Speaking in the UK Parliament ahead of the talks, Macron said the two countries were "stepping up" their joint efforts but warned EU support was essential to ensuring "a lasting and effective solution".
Adressing both Houses of Parliament, Macron said: "In this unstable world, hope for a better life elsewhere is legitimate.
"But we cannot allow our countries' rules for taking in people to be flouted and criminal networks to cynically exploit the hopes of so many individuals with so little respect for human life.
"France and the UK have a shared responsibility to address irregular migration with humanity, solidarity and fairness."
Decisions at this week's UK-France summit will "respond to our aims for co-operation and tangible results on these major issues," he said.
But her warned "we will only arrive at a lasting and effective solution with action at the European level".
Prime Minister Sir Keir Starmer is pressing to make a "one in, one out" deal the centrepiece of a new agreement with France.
The arrangement would allow Britain to return migrants who arrive by small boat to France in exchange for accepting asylum seekers with a family connection in the UK.
The purpose would be to demonstrate to those considering the perilous crossing that they could plausibly end up straight back in France, in the hope that this would deter them.
But any such exchanges would have to happen in large enough numbers to become an effective deterrent.
Getting a deal of this sort would be a big breakthrough as it would be the first clear sign of French willingness to take back migrants who have crossed the Channel.
But the optimism on the UK side of a deal being agreed this week is heavily qualified.
Downing Street is in separate talks with the European Commission to overcome opposition to the deal from a group of five Mediterranean countries who have complained they may be forced to accept people deported from the UK.
Sir Keir has also been pushing for France to revise its rules to allow police to intervene when boats are in shallow water, rather than requiring them still to be on land.
On Tuesday, a Downing Street spokesperson said the government expects new powers allowing French police to act before boats reach open water to be "operationalised soon".
But the spokesperson said months of negotiations between Sir Keir and Macron were "bearing fruit".
Last week the BBC witnessed French officers use a knife to puncture an inflatable boat after it had launched in an apparent change of tactics.
Asked about the tactics, a Downing Street spokesman said: "The French are now looking to bring in important new tactics to stop boats that are in the water, and we're expecting that to be operationalised soon.
"We are the first government to have secured agreement from the French to review their maritime tactics so their border enforcement teams can intervene in shallow waters.
"This is operationally and legally complex, but we're working closely with the French."
The Lib Dems have endorsed the talks, arguing "cross-border cooperation will be key to stopping these dangerous Channel crossing".
Party spokesperson Lisa Smart said: "To fully tackle the scale of the problem, we need to see far more ambition - including by negotiating a stronger leadership role of the UK in Europol."
Since coming to power in July last year, Labour has announced a series of measures to tackle people-smuggling, including a new criminal offence of endangering the lives of others at sea.
Legislation going through Parliament sets out plans to use counter-terror powers against people smugglers - with suspects facing travel bans, social-media blackouts and phone restrictions.
But the latest figures show 2025 has already set a new record for small boat arrivals in the first six months of the year, since the data was first collected in 2018.
Between January and June nearly 20,000 people arrived in the UK by crossing the English Channel in small boats - up 48% compared to the same period over 2024.
The UK has repeatedly pushed France to tighten patrols along its northern coast. Since 2018 the UK has pledged more than £700m to France to boost coastal patrols and buy surveillance gear.
The majority of this came from a 2023 deal struck under the previous Conservative government to give France almost £500m over three years to go towards extra officers to help stop migrants crossing the Channel in small boats.
Asked whether the UK, as the Conservatives have suggested, should demand a refund, a Downing Street spokesperson said "under this government, we've secured a significant ramping up of the operational capabilities from French law enforcement".
