Number 10 has said the government will press ahead with its latest anti-terrorism laws, even though Tony Blair has said he will meet with the Conservative leader to discuss possible alternatives.

With both the Tories and Liberal Democrats expressing opposition to plans for house arrest without trial, ministers may not be able to force the legislation through parliament.

Downing Street insisted the plans had not been arrived at lightly, but in the Commons yesterday the prime minister said that he would "look at proposals from any quarter" for ways in which the current plans could be modified.

"The one thing I will not do as prime minister is engage in anything that puts the security of our country at risk," Blair told MPs. "That is absolutely paramount for me."

Michael Howard accepted the need to protect the public from terrorist attack, but said that the government should not "lose sight of the need to protect our way of life".

Liberal Democrat leader Charles Kennedy told MPs that a new offence of "planning terrorism" should be created in order to protect people's civil liberties.