PARIS (REUTERS) - Britain and France have agreed to improve border controls and cooperate more closely in an effort to control a growing number of illegal immigrants trying to cross the English Channel from the French port city of Calais to Britain.

The port has long been a magnet for illegal migrants trying to reach Britain, which is not one of the 26 European Union members to have abolished controls at common borders.

France has said the number of migrants gathering in Calais has shot up as more people flee humanitarian crises in the Middle East, and northern and eastern Africa.

Britain will contribute 5 million euros (S$8 million) annually over three years under the deal, according to a joint statement from British interior minister Theresa May and her French counterpart Bernard Cazeneuve. "This fund will finance moves to secure the port of Calais and protect the vulnerable," Cazeneuve said in the statement on Saturday.

The port layout will be changed to make it easier to carry out controls and improve traffic flow, and barriers will be put up along the bypass leading to the port area, the ministers said.

British and French police forces plan to work more closely to dismantle criminal networks seeking to transport migrants to the UK, they added.

France estimates the number of illegal immigrants in Calais at 1,500, up by 50 per cent in the past year as Europe struggles to deal with the influx of the world's poor into a region they see as a haven in which to build better lives.

In Britain, the latest build-up of illegal immigrants in Calais has fuelled anti-European Union sentiment. In France, Marine Le Pen's anti-immigration National Front party, which won around 14 percent of the Calais vote in town hall elections in March, says it is seeing local support rise.