LONDON, Aug 5, 2025 (BSS/AFP) - A deal between London and Paris under which Britain can return some migrants who cross the Channel in small boats back to France will come into force Tuesday, the UK Home Office announced.

The agreement, which was struck between Prime Minister Keir Starmer and President Emmanuel Macron during the latter's state visit to the UK last month, involves a "one-in, one-out" scheme to curb record levels of irregular Channel crossings.

The two governments signed the final text last week, with the EU Commission giving its "green light on this innovative approach", the UK Home Office said in a press release Monday.

UK authorities are "operationally ready" and migrant detentions are expected to begin "within days", it added.

Under the scheme, migrants arriving to UK shores on small boats may be detained and returned to France if they are deemed ineligible for asylum.

In exchange, the UK will accept an equal number of migrants from France who can apply for asylum via an online platform, giving priority to nationalities most vulnerable to smugglers and to people with ties in Britain.

The number of migrants making the dangerous journey in flimsy dinghies this year crossed 25,000 at the end of July -- the highest ever tally at this point in the year as Starmer struggles to stem the tide, or the growing domestic discontent.

In recent weeks, anti-immigration protesters and counter-protesters have clashed outside hotels housing asylum seekers in Britain, with some demonstrations turning violent.

But Starmer has tried to hammer home the deal as a diplomatic victory, after years of faltering cooperation between France and the UK on the politically sensitive issue.

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"This is the product of months of grown-up diplomacy delivering real results for British people as we broker deals no government has been able to achieve," Starmer said in a press release.

While the agreement has met with criticism in northern France, where some officials say the scheme is too favourable to the UK, Nigel Farage's hard-right Reform UK party says it does not go far enough to secure Britain's borders.

The Home Office this week pledged £100 million ($132 million) for law enforcement, including additional manpower and technology, to "tackle" gangs who organise the crossings.

Starmer's government also said it will make it an offence to promote on social media dangerous immigration routes into the UK, including via the Channel.

Under the new provision, which will be part of a border security bill making its way through the parliament, those found advertising such crossings could be fined and face up to five years in prison.

According to Home Office analysis, 80 percent of migrants arriving via small boats told officials they used social media during the process.