France, Aug. 7 -- The UK said on Thursday it had detained the first migrants under a new "one-in, one-out" deal with France in which it can return people crossing the Channel on small boats.

The agreement, which came into force on Wednesday, seeks to curb record levels of irregular Channel crossings, which are causing discontent in Britain and helping fuel the rise of the hard-right Reform UK party.

"Detentions began for those who arrived in the UK on a small boat yesterday lunchtime (Wednesday). They will be held in immigration removal centres pending their removal," the interior ministry said in a statement.

The detained individuals are expected to be removed to France in the "coming weeks", it added.

Under the arrangement- for now ...