British PM challenges supporters of Britain's exit from the EU to admit the risks involved

British Prime Minister David Cameron delivers a speech at the headquarters of O2 in London, on Feb 23, 2016.
British Prime Minister David Cameron delivers a speech at the headquarters of O2 in London, on Feb 23, 2016. PHOTO: EPA

LONDON (AFP) - Prime Minister David Cameron on Sunday (Feb 28) challenged supporters of a British exit from the European Union to admit the risks involved, as the battle for votes stepped up ahead of the June referendum.

In an article for the Sunday Telegraph, a newspaper close to his Conservative party, Mr Cameron warned that gaps in the case for a Brexit made it the "gamble of the century".

"When the people campaigning for 'out' are asked to set out a vision outside the European Union, they become extremely vague," the Prime Minister wrote.

"It's simply not good enough to assert everything will be all right when jobs and our country's future are at stake."

Mr Cameron dismissed suggestions that Britain could still have access to the EU single market while opting out of the free movement of people.

He questioned what would happen to European security cooperation, and challenged the idea that Britain would have more influence on the world stage if it went it alone.

"There is no doubt in my mind that the only certainty of exit is uncertainty; that leaving Europe is fraught with risk," he wrote.

The article is one of numerous interventions on the EU in the weekend's newspapers, as the key players step up their efforts to woo a divided public ahead of the June 23 vote.

Mr Cameron is also trying to persuade members of his Conservative party. Six senior ministers are backing a Brexit, along with significant numbers of Tory MPs.

In a boost for Mr Cameron's case, G-20 finance ministers warned that a Brexit would be a "shock" that ranks among rising downside risks and vulnerabilities for the world economy.

But on Saturday, Mayor of London Boris Johnson, a long-term rival to the Prime Minister who is leading the Brexit campaign, said the "Remain" camp was exaggerating the risks.

"I will do my absolute best to dismiss Project Fear, which I think is nonsense. Britain could have a really great future, with a more dynamic economy and a happier population," Mr Johnson told The Times newspaper.