Home Secretary David Blunkett has outlined measures being considered to stop a terror attack on the UK.
Mr Blunkett wants debate
Options include allowing the use of secretly-taped phone calls as evidence in trials of terrorist suspects.
The home secretary says it is inevitable the UK will face a terror attack - and he wants a public debate about what should be done to thwart it.
Mr Blunkett, who addressed MPs in the Commons, also detailed plans for a big expansion of MI5.
Ahead of the publication of the Home Office options paper, Mr Blunkett told the BBC the security services needed more powers to apprehend terrorists before they strike.
But that argument is facing a rocky ride in the Commons from MPs concerned about the post 11 September terror laws, which allow foreign terror suspects to be detained without trial.
They are debating criticisms of the terror laws published in December by a review group chaired by Lord Newton.
It said detentions had not been used excessively but pushed for them to be replaced by measures which did not need Britain to opt out of European human rights laws.
ARRESTS, CHARGES AND OFFENCES SINCE 11 SEPTEMBER 2001:
544 individuals arrested
98 charged with offences under the Terrorism Act 2000
Seven offences: receiving money or property intended for terrorism
Six offences: Receiving instruction in the making or use of firearms, explosives or chemical, biological or nuclear weapons
Two offences: Belonging or professing to belong to a proscribed organisation
On Thursday, the laws come up for their annual renewal from Parliament.
There are currently 14 foreign suspects being held at Belmarsh prison without charges under anti-terrorist laws.
Mr Blunkett said he believed that the ability to detain foreigners without trial "was, and remains, necessary".
But Conservative shadow home secretary David Davis backed calls for alternatives to the detention powers to be found.
That search should focus on removing legal obstacles to prosecutions, including the ban on using phone-tap evidence in courts, said Mr Davis, who expressed reservations about some other anti-terror proposals.
The new options paper shows what other countries are doing and recommendations from reviews of current British laws.
It sets out the nature of the threat faced, the way al-Qaeda operates, the reasoning behind the controversial powers to detain foreign terror suspects and a response to the review of current anti-terror laws.
The idea is to "take the temperature of the country", by asking people to say where the balance lies between security and the defence of civil liberties, said a Home Office spokesman.
He said a "short list of discussion" points would only prompt criticism from civil rights groups. A policy paper will be produced after the six month consultation.
Mr Blunkett said he had been told by the head of MI6 that a terror attack on Britain was a case of "when" rather than "if", but it was difficult to get people to believe this was the case.
"They see Bali, they see Casablanca, they see what's happened in Istanbul, but they don't believe that it can happen here," he told BBC Breakfast.
"We mustn't allow ourselves to get into a position where we'd only address these issues openly and honestly if something terrible happened."
In those circumstances, there was a risk "hysteria" would sweep away reasonable objections to taking further draconian measures, he argued.
Different kind of terrorism
Mr Blunkett challenged critics to produce their own solutions.
The actions of suicide bombers were "outside the norms of anything we've known before", he said.
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"We have got to get into whether there are associations, whether there are acts that we can intervene on before that low level activity is put together by high level organised terrorists."
Mr Blunkett admitted the UK was only a few steps away from a secret trial system.
But he did not intend to lower the standard of proof for terror cases, although there could be civil court orders for those on the fringes of terror groups, he said.
Liberal Democrat home affairs spokesman Mark Oaten suggested senior judges' fears had silenced Mr Blunkett over the standard of proof.
The options paper was "short on ideas", said Mr Oaten, adding: "Nothing in this announcement addresses the fundamental objection to locking suspects up without charge or trial."