A migrant who returned to the UK on a small boat after being removed under the “one in one out” scheme with to France will have his removal “fast-tracked”, the prime minister has said.

The man claimed to have been a victim of modern slavery at the hands of smuggling gangs in France, according to reports in the Guardian.

Speaking to the BBC, Sir Keir Starmer said “trying to get back here has been completely pointless” for the man, who is understood to be an Iranian national.

“He’s already in the system, we know who he is, we’ve got him and we’re going to get him back out of the country very, very quickly.”

The BBC understands the man was initially detained on 6 August and was removed on 19 September, becoming the third person to be sent to France under the scheme. He returned about a month later, on 18 October.

More than 40 people who arrived in the UK illegally have been removed under the scheme since September.

Under the treaty, France agreed to take back migrants who had travelled to the UK by small boat and had their asylum claim withdrawn or declared inadmissible.

For each person returned to France, the UK will accept someone with a case for protection as a refugee who has not attempted to cross the Channel.

The migrant, who has not been named, told the Guardian he returned to the UK due to fears for his life in France.

Speaking about his alleged treatment at the hands of smugglers, he said: “They took me like a worthless object, forced me to work, abused me, and threatened me with a gun and told me I would be killed if I made the slightest protest.”

The Home Office previously 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.”

Separately, the BBC has spoken to an Eritrean man in France who says he was also returned under the scheme.

The man, who asked to be identified as Jonas, said he fled his home country because he feared religious persecution during mandatory conscription in the military.

Home Office data released on Thursday shows the total number migrants who have arrived in the UK by small boat so far in 2025 now stands at 36,954 – exceeding the total for the whole of last year.