British Prime Minister David Cameron on Wednesday expressed concern over an attempt by an estimated 2,000 migrants to enter Britain from the French port town of Calais via the Eurotunnel.

"This is very concerning," he told reporters during a visit in Singapore, adding that "we are working very closely" with French authorities to address the situation.

He added that Home Secretary Theresa May will chair a meeting of the government's Cobra emergency committee to discuss the Calais incident, which occurred on Tuesday.