The government is facing a battle in the House of Lords after it abandoned plans to make new faith schools take more children from other religions.
Education Secretary Alan Johnson said he had dropped the idea after reaching a "voluntary agreement" with churches.
But his Tory predecessor Lord Baker told the BBC he would table an amendment to the Education Bill next week to reinstate the quotas plan.
He accused ministers of the "fastest U-turn in British political history".
Barry Sheerman, Labour chairman of the Commons education select committee, said ministers should not seem to be "rushing around in some sort of panic introducing measures at the last minute".
He added: "I'm always very concerned when politicians seem to be making policy on the hoof."
Lord Baker's spokeswoman said the peer's amendment, compelling new state-funded faith schools in England to take up to 25% of pupils from outside the religion, would be tabled on Monday.
This would be similar to the scheme the government's abandoned scheme, she added.
ENGLAND'S FAITH SCHOOLS
Church of England 4,646
Roman Catholic 2,041
Muslim 9 (expected)
Earlier, Mr Johnson said he had reached a deal with Catholic Church and the Church of England to "ensure" they would reserve up to a quarter of places in their schools for children of other faiths or of no faith.
He added: "As we now have the support of the two major faith organisations in the country for our proposed way forward, I do not feel the legislative route is necessary or appropriate and no longer propose to lay an amendment to the Education and Inspection Bill."
But Lord Baker, who earlier this month dropped his own amendment imposing quotas after ministers had agreed to include similar plans in the bill, was furious.
Speaking on BBC Radio 4's Today programme, he accused Catholic leaders of using "deception" in their campaign against introducing quotas, by hinting that the plans would be extended to all existing faith schools, not just new ones.
Any requirement to provide non-faith places, where local circumstances make it appropriate and subject to public consultation, would be in addition to the demand for faith places
Most computers will open PDFs, but you may need to download Adobe Acrobat Reader.
He said the government "must impose some means of integration" when funding schools.
Otherwise there was a danger of creating educational "ghettos", particularly in more than 120 private Muslim schools which he said aspired to enter the state sector.
Vincent Nichols, the Catholic Archbishop of Birmingham, said Mr Johnson understood it was "quite unacceptable to force into a new Catholic school 25% of people who were not particularly sympathetic to that faith".
Although the voluntary agreement does not affect Muslim schools, the Muslim Council of Britain welcomed it, with education spokesman Tahir Allam saying the compromise was "a good position to be in".
Under the government's abandoned plans, councils could have told new faith schools to take up to 25% of pupils from other religions, or no religion.
The Conservatives said they would not support Lord Baker's amendment, while the Liberal Democrats called the current situation a "dog's dinner".
Terry Sanderson, from the National Secular Society, said ministers had "given in to... religious pressure and I'm not sure whether it's because they recognise the arguments, or because they wanted to give the religious people what they wanted".