The first migrant has been sent back to France under the “one in, one out” deal struck between the UK and France, the BBC understands.

The man, who originated from India, was removed this morning on an Air France flight, which has already landed in Paris, sources told the BBC.

It comes after the temporary blocking of the deportation of an Eritrean man on modern slavery grounds sparked concerns that the migrant deal may be frustrated by legal challenges.

The government had been facing fresh pressure over the returns agreement and several flights planned for earlier this week have been reported as cancelled.

Home Secretary Shabana Mahmood vowed to fight “vexatious, last-minute claims” after the High Court intervened this week in the case of an Eritrean man who

Mahmood said: “Migrants suddenly deciding that they are a modern slave on the eve of their removal, having never made such a claim before, make a mockery of our laws and this country’s generosity.”

But the UK’s independent anti-slavery commissioner told BBC Radio 4’s Today programme that she was “deeply concerned” about the home secretary’s words.

Eleanor Lyons said that suggesting the system was being abused created a “tool for traffickers to use with those victims that they are exploiting”.