LONDON

The UK government's flagship "one in, one out" migration scheme has come under renewed scrutiny after a person previously deported to France returned to the UK on a small boat.

Under the policy, irregular migrants who cross the Channel are returned to France, while legal asylum seekers are allowed to enter the UK.

The incident, which was reported by the Guardian on Wednesday, has called into question the scheme's effectiveness in managing Channel crossings.

Now held in a UK immigration detention center, the person seeks asylum and has told the Guardian that he was a victim of modern slavery at the hands of smugglers in northern France.

Home Office sources confirmed that the man was sent back under the UK-France treaty, which allows people crossing the Channel illegally to be returned to France in exchange for the same number of asylum seekers entering the UK via legal routes.

A government spokesperson said: “We will not accept any abuse of our borders, and we will do everything in our power to remove those without the legal right to be here. Individuals who are returned under the pilot and subsequently attempt to re-enter the UK illegally will be removed.”

The case has drawn criticism from opposition politicians and social media commentators.

Tory leader Kemi Badenoch said in a post on US social media company X: “Does that mean we now have to take two people from France to return him? This Labour government is in total chaos: no backbone, no plan and too weak to take the tough decisions to secure our borders.”

Last week, the UK’s border chief expressed frustration on Thursday that French authorities have not yet been able to deploy tactics to puncture and disable boats carrying asylum seekers in shallow waters.

On Sunday, the Home Office said that 16 people who arrived in the UK via small boats were returned to France last week -- the largest group deportation under the scheme to date -- bringing the total number of returns to 42.

Under the “one in, one out” treaty, 23 asylum seekers have so far been legally admitted to the UK in exchange.