Gordon Brown has pledged not to put civil liberties at risk over plans to introduce new anti-terror laws.
Mr Brown has pledged to safeguard traditional freedoms
Mr Brown wants to give police more powers - including holding suspects without charge for more than 28 days - when he takes over as prime minister.
Civil liberties campaigners warn the plan amounts to "internment".
But in a speech earlier, Mr Brown insisted he would bring in safeguards, including a judicial review of detention every seven days.
Mr Brown is also planning to summon cross-party talks in the Privy Council on the use of phone-tap evidence in court.
Such a move was resisted by Prime Minister Tony Blair because security services fear it will expose their secret surveillance methods.
Mr Brown also wants to allow police to continue questioning suspects after they have been charged.
He wants judges to make support for terrorism an aggravating factor in sentencing, as it currently is with racially aggravated crime.
Mr Brown, who is due to take over as prime minister on 27 June, told a Labour leadership hustings in Newcastle he was ready to be "tough in the security measures that are necessary to prevent terrorist incidents in this country".
He added: "We will have to consider further legislation to do so. I think that is where the public will need to recognise that we have got a new security problem."
But he said he would make sure that "at no point will our British traditions of supporting and defending civil liberties be put at risk.
"There has got to be independent judicial oversight. There has got to be proper parliamentary accountability.
"We should give the police the power to question people so we can both prevent incidents and get to the bottom of some of these very, very strange dealings."
Liberal Democrat home affairs spokesman Nick Clegg said Mr Brown "appears a little more concerned about parliamentary accountability than his predecessor".
But he added: "It now remains to be seen whether this is just a procedural fig-leaf for more authoritarian measures or part of a genuine shift in guaranteeing and not undermining our fundamental civil liberties."
And the party's justice spokesman Simon Hughes warned Mr Brown he would have a "fight on his hands" if he wanted to extend the detention of terror suspects.
Mr Blair's unsuccessful attempt to introduce 90-day detention without charge in 2005 was opposed by Tories, Liberal Democrats and some Labour backbenchers.
And Conservative sources say there is no new evidence to suggest that police need more than 28 days.
But Constitutional affairs minister Harriet Harman, one of six Labour MPs vying to be Mr Brown's deputy, said she thought MPs would back new laws - including 90 day detention - if Mr Brown could prove they were needed.
"I don't think there will be a huge problem if there is a proper debate about it - if evidence is brought forward about why current powers are inadequate and what the safeguards will be," she told BBC One's Sunday AM.
Her deputy leadership rivals Peter Hain, Hilary Benn and Hazel Blears also indicated they would back new anti-terror laws.
Campaign group Liberty said it supported the use of phone-tap evidence and post-charge questioning.
But director of Liberty Shami Chakrabarti said Mr Brown was making "a grave mistake" in proposing to extend questioning without charge beyond 28 days.
"Twenty-eight days is already the longest period to hold a person without charge in the free world," she said.
"If you go beyond 28 days it is internment."
The government's independent reviewer of anti-terrorism legislation, Lib Dem peer Lord Carlile, welcomed Mr Brown's initiative.
Lord Carlile told the BBC: "I do think it is time for the political parties to get together and to try to reach a consensus with the government, so we can move forward on terrorism legislation on the basis of fitness for purpose, rather than having a hot political debate about these desperately difficult and important matters."
But shadow home secretary David Davis, for the Conservatives, said Mr Brown's decision to announce the move through briefings to Sunday newspapers, rather than to MPs in the Commons, did not bode well for cross-party talks.
"It is extraordinary that the chancellor has chosen to publicise these proposals five days before the home secretary announces his counter-terrorism plans in Parliament.
"It does not auger well for cross-party attempts to build a consensus for counter-terrorism measures which the whole country needs to get behind," said Mr Davis.