French coastguards have rescued four migrants who were found trying to cross the Channel in an inflatable dinghy.
Rescuers were alerted by a fifth person found on a beach at Sangatte near Calais, suffering from hypothermia, in the early hours of Saturday.
He told officials that the migrants on the dinghy were part of a group that had set off for the UK from Dunkirk.
French police said crossing the Channel was very dangerous because of the large volume of shipping in the area.
The head of a local police union, Gilles Debove, said it was only the second or third time in 10 years that such a crossing had been attempted.
The migrants were found about three miles from the French coast and rescued shortly after 06:00 GMT.
They were wearing life vests and suffering from hypothermia, France Info radio reported.
The station said the fifth man had abandoned the boat and swum back to shore, reaching Sangatte.
A French association that supports migrants said it feared more people may try to reach the UK by boat because of tighter controls at the port of Calais and the Channel Tunnel.