Brown: I want terror suspects held for 90 days

He said he believed the police's powers had to be extended to tackle the terrorist threat.

The Prime Minister-in-waiting is also understood to be preparing for a battle with civil liberties campaigners by lifting the ban on questioning alleged terrorists after they have been charged.

He is considering the use of intercept evidence -obtained by tapping suspects' phone calls - in court.

Tony Blair lost a Parliamentary battle two years ago to hold terror suspects longer. He wanted an increase from 14 days to 90 but settled for 28.

However, in Glasgow the Chancellor signalled he would revisit the controversial issue.

He said: "We must be vigilant for the benefit of security in this country. Anti-terror methods must be more sophisticated, with earlier intervention.

"That is why I support an increase in the length of detention to build up evidence, and I support post-charge questioning with an increase in police resources."

Sources close to the Chancellor said that he was determined to avoid the pitfalls suffered by Mr Blair by making MI5 and MI6 more accountable to Parliament and giving more say to the courts on terrorist detentions.

He said: "Because we believe in the civil liberties of the individual we must also strengthen accountability to Parliament and independent bodies overseeing the police, not subjecting people to arbitrary treatment."

It is understood that Mr Brown will also look to give Parliament a greater role in scrutinising the work of the security services.

This is expected to see changes in the remit of the Intelligence and Security Committee, which is appointed by the Prime Minister and meets behind closed doors.

Mr Brown wants to put it on a more equal footing with other Parliamentary committees and it could play a similar role to the US Senate Intelligence Committee which has the power to compel senior intelligence officials to give evidence, often in public sessions.

On the use of intercept evidence in court - something which has so far been resisted by the security services - Mr Brown will order a Privy Council review.

Use of phone tapping evidence would allow more cases to be brought to court but there are fears it would also risk exposing the security service's sources.