The first migrant deportation flights from the United Kingdom to France under a newly agreed "one in, one out" returns deal were scheduled to begin on Monday.

The "one in, one out" deal, signed in July, allows the UK to return to France people who entered the UK irregularly via small boat crossings. In return, the UK will admit an equivalent number of asylum seekers through a designated safe and legal route who fit the UK criteria.

The first detentions under the agreement were made on Aug 6, with Home Secretary Shabana Mahmood saying last week that returns would start "imminently".

Subject to any last-minute legal challenges, the first migrants were due to travel alongside tourists and business passengers on a commercial Air France flight on Monday.

The Times newspaper said it had seen a message sent to a migrant scheduled for deportation that read: "You will be removed from the UK on Air France Flight (AF) 1681, which departs from Heathrow Terminal 4 at 09:00 on 16/09/2025 and arrives in Paris, France at 11:20 on 16/09/2025."

The paper reported that those asylum seekers who arrived by small boat in August had received formal removal directions, giving them five days' notice of deportation to seek final legal advice.

Returns to France are expected to start at about 50 a week, with numbers rising as the pilot program progresses, the Home Office says, although it has not confirmed the figures. For now, the initiative applies only to adults, as children who enter the UK illegally are not detained.

While supporters hope the policy will discourage crossings and people-smuggling, critics argue that unless a large share of arrivals is returned, many will still attempt the journey, according to an analysis by the Migration Observatory, an independent research center specializing in UK migration policy.

The initiative comes amid rising public anger over immigration, which has recently become voters' top concern for the first time since the 2016 Brexit referendum, reported Sky News.

On Saturday, as many as 150,000 people marched in central London, gathering around Westminster for a protest organized by far-right activist Tommy Robinson that was primarily focused on opposition to what participants described as excessive immigration.

Speaking on Sky News on Sunday, Laura Trott, the shadow education secretary, said the protest suggests people feel "let down" by the government on immigration.