The U.K.'s National Crime Agency has made two arrests on suspicion of arranging illegal movement of migrants across the English Channel into Britain.

A 33-year-old Iranian and a 24-year-old Briton were arrested in Manchester, the NCA said in a statement late on Wednesday. The statement did not give further details.

Britain's interior minister, Sajid Javid, said recently that there had been an increase in the number of migrants crossing the English Channel from France. Last week he declared the situation a "major incident."

More than 200 migrants had made attempts to cross one of the world's busiest shipping lanes in December, although nearly half were stopped from leaving France, Javid said on Monday.

The number is a tiny fraction of those regularly attempting to reach European Union territory by crossing the Mediterranean from northern Africa and Turkey. Many of them are fleeing conflict and poverty in the Middle East and Africa.

The attempts to cross into Britain have attracted extensive domestic scrutiny amid a highly charged political atmosphere less than three months before Britain is due to leave the EU in the aftermath of a referendum in which immigration was a major theme.

Britain is deploying extra patrol boats to help deal with the situation, the interior minister said earlier this week.

Javid has also written to British Defence Secretary Gavin Williamson requesting aerial surveillance, dozens of sailors and a military patrol vessel for help, the Telegraph newspaper reported.