FILE PHOTO: French Interior Minister Christophe Castaner attends a ceremony at the Police Prefecture in Paris, France, December 20, 2018. REUTERS/Benoit Tessier/File Photo

PARIS (Reuters) - France will tighten security at its northern ports and increase surveillance along beaches to counter the rise in migrants trying to cross the English Channel to reach Britain, its interior minister said on Friday.

More than 500 migrants, most Iranian, tried to cross the narrow stretch of water, one of the busiest shipping lanes in the world, during 2018, French Interior Ministry data showed.

Some 276 migrants reached British waters while the French authorities thwarted the attempts of another 228. More than 80 percent of the crossings were attempted in December.

“This action plan must enable us to put an end to these crossings of the Channel which are not only illegal but also dangerous,” Interior Minister Christophe Castaner said in a statement.

“It is in our interests, as well as British interests, to do everything possible to prevent the development of new trafficking routes that might attract illegal migrants to our coast once again.”

In late October 2016, France razed a sprawling migrant camp outside the northern port of Calais that served as a launch pad for migrants seeking to enter Britain hidden in trucks, trains and ferries.

The numbers trying to reach Britain increased sharply last year compared with 2017 but remained a tiny fraction of those regularly attempting to reach European Union territory by crossing the Mediterranean from northern Africa and Turkey.

Nonetheless, the Channel crossings have put pressure on the British government amid a charged political atmosphere less than three months before Britain is due to leave the EU after a referendum in which immigration was a major theme.

British Defence Secretary Gavin Williamson said HMS Mersey, a Royal Navy offshore patrol vessel, was deploying to the Dover-Calais straits to stem the flow of migrants. The waterway is just 21 miles (33.8 km) wide at its narrowest point.