French and British maritime authorities intercepted 18 migrants trying to cross the Channel on Tuesday, the latest in a string of attempts to reach England by boat.

French gendarmes picked up nine migrants on board a small fishing boat that was detected by a British ferry around 5:00 am (0400 GMT) eight kilometres (five miles) off Dunkirk, French maritime authorities said in a statement.

About 50 minutes later rescuers from Britain's RNLI lifeboat charity rescued a second boat drifting around 13 kilometres from the British port of Dover.

The second boat was also carrying nine migrants, whose nationality was not immediately known.

There has been a sharp rise in the number of migrants attempting to cross the Channel from France since October, despite dangers posed by heavy traffic, strong currents and plunging temperatures.

The latest rescues come two days after French authorities picked up eight migrants suffering from hypothermia during an attempted crossing in an inflatable boat.

British authorities have picked up around 80 migrants over the past two weeks.

For years, thousands of migrants from Africa, the Middle East and Asia have attempted to reach Britain from France -- the vast majority by trying to stow away on trucks crossing the Channel.

Police continue to routinely clear migrant camps along the French coast, two years after dismantling the squalid "Jungle" settlement in Calais which was once home to some 10,000 people.

(AFP)