Britain's Prime Minister David Cameron gestures as he speaks at a general practice surgery in Birmingham, Britain May 18, 2015.  [Photo/Agencies]

LONDON - Britain's Prime Minister David Cameron on Thursday announced plans to crack down on illegal immigration and tighten Britain's borders as new official figures showed a significant rise in the number of long-term migrants.

Net migration to Britain surged to roughly 318,000 in 2014, up from 209,000 the year before, the Office for National Statistics said. The figure represents the estimated number of people entering the country on a long-term basis minus the number departing.

Immigration has become one of the most divisive political issues in Britain, and increasing numbers of Britons argue that uncontrolled migration has a negative effect on the country - from employment to social infrastructure such as housing and health services.

In his first speech on immigration since he won a second term in the general election, Cameron said police will be given powers to seize the earnings of illegal migrant workers. Businesses will be barred from recruiting abroad without advertising in Britain.

"A strong country isn't one that pulls up the drawbridge," he said. "It is one that controls immigration ... Because if you have uncontrolled immigration, you have uncontrolled pressure on public services. That raises basic issues of fairness."

The data showed that 641,000 immigrants came to Britain last year, up by more than 100,000 since 2013. Of those, just more than half were people from within the EU.

Cameron has long insisted he can cut net migration to the "tens of thousands."

"It's disappointing that we haven't made more progress, but I take these figures as a clear instruction to deliver and to deliver faster," Cameron said Thursday.