The epic parliamentary stalemate over the Prevention of Terrorism Act has drawn to a close after 24 hours of high drama in Westminster.

In a press conference on Friday evening, Michael Howard announced that the latest government concessions had been enough to secure the end of his party's opposition to the legislation.

The Liberal Democrats also signalled they were standing down their troops, accepting that the measure was heading for approval.

The move came after Charles Clarke outlined plans for a wide-ranging consultation after the general election on the workings of the government's next anti-terrorism legislation.

This would provide opposition parties the chance to table amendments to the legislation currently being considered, the home secretary told MPs.

Responding to the developments, Howard said this move was a "sunset clause in all but name".

His decision to accept the law meant it was easily approved by peers when they considered it for the fifth and final time on Friday evening.

A Liberal Democrat bid to insist on a higher level of proof before control orders could be issued faltered without Tory support, with peers voting by 177 to 56 against the amendment.

Lib Dem leader Charles Kennedy said his party would "maintain our objections and will return to this issue under the new timetable and procedures the government has now conceded".

With peers then backing the legislation without further amendment, the final hurdle was cleared on the way to the statute book.

Speaker Michael Martin told the Commons at 7.20pm on Friday that it had gained royal assent, taking effect before the current anti-terrorism laws expires on Sunday night.

The need for urgent legislation was illustrated on Friday with the release on bail of the last eight foreign terror suspects who had been detained in British jails without charge or trial.

Concluding proceedings in the Lords, the constitutional affairs secretary said the debate had set new records.

"This is the longest recorded sitting of this house ever," Lord Falconer said.

For the Conservatives, Lord Kingsland said peers had "stood firm" and secured concessions from the government.

Blair's warning

Earlier on Friday, the prime minister had called on the Conservatives to drop their opposition to the Bill.

Tony Blair said it would be "grossly irresponsible" for parliament not to pass the government's anti-terrorism legislation.

Speaking in Downing Street, he indicated that there would be no other concessions.

"We've made it absolutely clear we cannot accept the amendment that would alter the burden of proof for the security services and police to take action against people," Blair said.

"If we accepted that amendment it would make it far harder for our security services and police to defend this country against terrorism."

And he said the 12 month sunset clause also backed by peers would be "a mistake".

He said it would "send a signal of weakness at the very time we should be sending a signal of strength".

However, the prime minister said there would be extensive pre-legislative scrutiny of forthcoming anti-terrorism legislation.

There would be "every opportunity for people to put forward amendments", he said.

And Blair said he had been trying to "give our police and those who look after the safety and security of our country, our citizens, our families the powers they need to protect us from those who threaten us with terrorism".

Howard's attack

In comments made shortly after the prime minister's statement, Howard said Blair had "only himself to blame" for the legislative mess which had been created.

The premier had been "arrogantly asserting that he is the only person willing to fight terrorism".

"If only he had been less arrogant these sensible changes could have been agreed to quicker and in a more dignified manner," added Howard.

Despite the last minute breakthrough, Howard went on to mount a wider attack on the government.

"These are difficult issues. That is why parliament needed proper time to consider them – time Mr Blair refused to give it. If only he had been less arrogant, these sensible changes could have been agreed to in a quicker and more dignified manner," he said.

"But there is more to be done. Britain’s lack of border controls poses a grave danger to our national security. There are over a quarter of a million failed asylum seekers living in our country today.

"No-one knows who they are, or where they are. There are no checks on people coming into or leaving our country."

Howard said a Conservative government will make tackling illegal immigration a priority.

"It is only through a combination of tough anti terror laws and strict border controls that we will defeat the terrorist threat," he added.