Home Secretary Jacqui Smith has been warned any plans to extend the time police can hold terror suspects without charge will be fiercely opposed.
Tories, Lib Dems and some Labour MPs plan to try to block a move to raise the 28-day pre-charge limit, saying there is no evidence change is needed.
Ms Smith told MPs change was needed but it was up to them to set the new limit.
She added plans to let police question suspects after they have been charged might not be limited to terror cases.
She also told MPs she believed there could be agreement on a package of further measures to tackle terrorism.
'Wrong in principle'
These would include ensuring police and intelligence agencies make full use of information and data, strengthening prosecutions against terror suspects by allowing post-charge questioning and the monitoring of convicted terrorists after release from jail.
She has also suggested that post-charge questioning could be used "more widely" to deal with non-terror crimes.
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In the Commons, she said: "I believe that the time is now right to consider the extension of pre-charge detention, that period of time available to police officers to investigate and to gather the evidence and to question in order to be able to charge beyond the current limit of 28 days.
"We are seeking to gain consensus. I view this very much as an argument whether and how we provide the ability to extend beyond 28 days, not whether or not 56 or 90 or whatever the maximum day is, is appropriate, although I do think Parliament should set that final figure."
Shadow home secretary David Davis said: "We do not accept the need to extend detention without charge, based either on the evidence of operations to date or the most horrendous hypothetical scenarios dreamt up by ministers."
Liberal Democrat home affairs spokesman Nick Clegg said extending the period was "divisive, wrong in practice and wrong in principle".
Labour veteran David Winnick said: "If we are to go beyond 28 days, the House should have compelling evidence that it's absolutely essential."
In 2005, government efforts to raise the limit to 90 days were defeated in the Commons, although it was later agreed to double the limit from 14 to 28 days.
The Conservatives and Liberal Democrats have both called for terror suspects to be questioned after being charged as an alternative to detention without charge.
Earlier Ms Smith told BBC Radio 4's Today programme the government was looking at whether this change could extend beyond anti-terror laws.
She added that post-charge questioning was not "a panacea in itself, but it is an important condition for a bill that we believe will provide for investigators and for prosecutors more of the tools that they need to help them to counter the serious threat from terrorism".
Shami Chakrabati, director of the human rights group Liberty, said the power could be justified for dealing with terrorists but that it was impractical for those suspected of other crimes.
Under the government proposal, juries could be told to view negatively any refusal by a suspect to co-operate after charge.
But barrister Ali Naseem Bajwa said: "After charge, a suspect has very little to gain by commenting.
"He has already been labelled a terrorist. He might as well save it for the jury."
The Conservative Party, which says it came up with the post-charge questioning proposal, is also calling for the use of intercept evidence, such as from phone taps, in court - something also backed by the Lib Dems - and a "proper" border police force.