Michael Howard has insisted that immigration into Britain must be limited.

In an interview with Jeremy Paxman aired on the BBC on Friday evening, the Conservative leader said the move was necessary for the sake of the country's security.

He also said the number of immigrants should be kept down in the interests of good community relations and ensure manageable demands on public services.

The interview was the final instalment of a series of pre-election grillings for each of the major party leaders.

Annual limit

Paxman pressed Howard for a precise figure for his proposed annual limit for the number of immigrants to be allowed into Britain.

Howard replied: "We haven't got a number yet... We will ask parliament every year to set a limit on the number of people who can come into this country.

"Parliament will set the limit after there has been consultation.

"There would have to be consultation with the CBI and other employers' organisations so that we can get the right number of people coming into this country with skills, which we need, as economic migrants," he said.

"We will set a number for family reunion. And we will set a number for genuine refugees.

"And in that way we arrive at the annual limit."

However, after repeated questioning Howard did suggest a figure of "about 150,00", but cautioned that this wasn't precise.

Off-shore processing

The issue of where asylum applicants would be processed was also raised.

Howard said: "We would look for overseas processing centres and put them there."

And asked where this centre would be located, Howard refused to name a country.

"I'm in opposition. I can't negotiate with other governments," he said.

When asked to acknowledge that no country had agreed to act as a processing centre, Howard said: "Of course not. I'm an opposition leader. But when we are in government we will negotiate."

Howard said he was "interested in doing what is best for Britain".

Scrutiny

Commenting on the interview, home secretary Charles Clark said Tory immigration and asylum policy was "unravelling".

"The fact is that tonight's interview shows that Michael Howard cannot answer the most basic questions on his immigration and asylum policy," he said.

"Once again Michael Howard could not answer where his offshore processing centres would be located.  And he could not answer what the size of his quotas would be.

"What the British people want are strict controls that work.  Not uncosted and unworkable solutions from the Tories that unravel at the slightest scrutiny."