Michael Howard today launched his party's new hardline policy on immigration and asylum, promising to pull Britain out of the 1951 UN Refugee Convention.

The Conservative leader said that he wants to remove the incentive for economic migrants to pose as asylum-seekers, if his party wins the next election.

A certain number of work permits would be issued to allow economic migrants to enter Britain legally, but foreigners arriving in Britain and trying to claim asylum would probably face a long wait in an overseas detention camp.

The policy was immediately criticised by race equality campaigners and by UNHCR, the UN refugee agency.

Speaking at the Conservatives' new party headquarters in Central London, Mr Howard proposed setting an annual limit to immigration, including a quota for "genuine refugees".

A Conservative government would also put in place 24-hour security at ports to combat illegal immigration, and institute an Australian-style points system for work permits - giving priority to those with skills the country needs. It could also start to use new third-country "transit zones", possibly in Libya, to hold asylum-seekers while their claims are processed.

The policy appears to be a clear attempt by the Conservatives to shore up their core vote at the next election, and head off right-wing challenges from the British National Party or UK Independence Party.

But Mr Howard rejected accusations that he was playing the race card, saying: "It's not racist, as some people claim, to talk about controlling immigration, far from it. It is plain common sense, a vastly underrated quality in British politics today - but a quality prized by the majority of people."

Mr Howard, himself the son of Romanian Jews who fled to South Wales in 1939, said that immigrants have contributed significantly to the economy and culture of Britain, but any system of immigration needed controls and limits.

"Tony Blair has presided over an unprecedented rise in immigration - it has more than doubled since Mr Blair came to power. Nearly 160,000 people now settle in Britain each year. That is a city the size of Peterborough," Mr Howard said.

"According to the Government's own predictions, Britain's population will grow by six million over the next 30 years of which five million will be due to immigration - that is equivalent to five times the population of Birmingham."

He added: "There are literally millions of people in other countries who would like to come and live here. Britain cannot take them all."

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