An Eritrean man has been flown out of the UK under the government's "one in, one out" deal with France, after a last-minute court bid to delay the departure failed.

Britain on Thursday returned the first migrant to France under a new "one-in, one-out" deal, both governments confirmed, as London bids to curb highly contentious cross-Channel small boat arrivals.

The government is now facing a fresh legal challenge against its "one in, one out" deal with France just hours after hailing the first deportation of a migrant under the scheme.