Tony Blair has accused Michael Howard of "playing politics with national security".

Clashing at prime minister's questions on Wednesday, the two party leaders debated the need for the government's proposed new control orders for terrorist subjects.

The Tory chief argued that the government has no need to "steamroller through parliament" the measures by March, as the existing legislation could be extended while a "consensus" is achieved.

But Blair insisted that he was putting the safety of the public first, rather than seeking to make political capital out of the debate.

Real and current

Howard acknowledged that "terrorism is a real and current threat and that special powers are needed to deal with it".

However he asked Blair to "clear up one area of confusion".

"Nothing need be finally resolved within the next two weeks because the existing powers can be extended," he said.

The prime minister insisted that the decision to push the legislation through was "in deference" to the law lords' judgement, which found that previous legislation must be replaced.

"I am sure the House would expect us to respect [that]," Blair told MPs.

Howard said the government's own view was that "the Terrorism Act remains valid, enforceable and effective".

"We have offered to renew those provisions for a short period of time so that parliament can fully explore an alternative," he said.

But Blair said "we can debate these endlessly... in the end the issue is one of principle, he is opposed to these new control orders altogether".

Howard countered that "the government is in the mess it is in today is because the existing legislation was rammed through parliament".

"Surely he should learn from the mistake rather than repeat it again," he added.

Current threats

The prime minister defended the Act, pointing out that "several hundred people" have been arrested since it was introduced following the 2001 attacks on New York and Washington.

"There is a threat and it is important that we take the measures necessary, while protect civil liberties," he argued.

Blair went on to warn that "control order" powers such as house arrest were drawn up on the advice of the security services and police.

"There is an issue of principle. The security services and the police say that these orders are necessary for our national security," he told Howard.

"The question is whether he is prepared to accept that or not. The question is not whether this is being steamrollered through, it is him playing politics with it."

Arrogance

Howard dismissed the "arrogance" of the prime minister's counter-attack.

"Playing politics is using national security for political point scoring," he said.

For the Liberal Democrats Charles Kennedy questioned why there would be greater accountability in a system where the home secretary could make an executive order.

He accepted that "our country is no stranger to terrorism" but questioned whether such draconian measures were totally necessary.

The decision to give ministers power to detain terror suspects could call into question "long standing fundamental principles of justice", said Kennedy.

Blair, however, reminded MPs that the risks posed by terrorists were real.

"There are large number of people... which we keep under surveillance. What is extremely important is that we have the power to disrupt these," he said.

"The reason why we have decided that it is right for the home secretary to have these powers in the first instance is for speed of action.

"The key thing is to get these control orders in place. We will bring it before a court, very quickly, but there may be circumstances when the home secretary may have to act."