David Cameron has been forced to intervene directly to cooling rising cabinet tensions between Michael Gove and Theresa May over the handling of an alleged extremist "plot" to take over British schools.
Both the Home Secretary and the Education Secretary insisted in a statement released late last night that they were "working together" on the 'Trojan Horse' plot, an unusual step aimed at scotching rumours of what Labour dubbed "a vitriolic stand-off".
Downing Street source said the Prime Minister was "keen to establish the facts" of the apparent spat, and is believed to have personally asked for calm, after the Home Secretary has suggested that Gove's department failed to deal with warnings of a plot by hardline Islamists to seize control of classrooms in several Birmingham schools.
And Justice Secretary Chris Grayling admitted there were "tensions and debates" within Government over the response, but denied there are "massive divides" between Gove and May.
"The fact is that we are pussycats when compared to the last government, if you remember the battles between Tony Blair and Gordon Brown," Grayling told BBC Radio 4's Today programme. "We have agreed joint strategies and I simply don't buy this argument that there are massive divides on this across Whitehall."
Her letter questioning its response to the so-called plot was said to have come after the pair clashed over Gove's concerns that the Home Office was doing too little to confront extremism at its roots.
Conservative Party chairman Grant Shapps also sought to cool hot heads, insisting such exchanges of views were "a perfectly normal part of government and is absolutely right".
"You would expect us to ask each other questions about each other's departments," he told BBC Radio 4's The World At One. That doesn't make it a row."
When asked about the furore on his LBC show, Nick Clegg was evasive. "Who started the fight, Gove or May?," asked presenter Nick Ferrari, pushing the Deputy Prime Minister on whether the pair got on. "Oh, ask them," he said, smiling.
Shadow home secretary Yvette Cooper said the ministers were engaged in a "vitriolic blame game" and demanded the Prime Minister step in to resolve it.
In a letter to her fellow Cabinet minister, May said concerns had been raised about the "inability" of local and central government to tackle the alleged plot. She also questioned whether Gove's department was warned about the allegations in 2010 and asked: "If so, why did nobody act?"
In December, the cross-government task force on tackling extremism and radicalism recommended a voluntary code of conduct to prevent children being exposed to "intolerant or extremist views" in religious "supplementary schools" providing lessons outside mainstream education.
But May said the Birmingham allegations showed the potential need for a mandatory code and urged Gove to include that option in his consultation on the plans. She said the Birmingham allegations "raise serious questions about the quality of school governance and oversight arrangements in the maintained sector, not just the supplementary schools that would be signatories to this code of practice".
Following the publication of the letter, a spokesman for the two Cabinet ministers issued a joint statement from Gove and May, saying: "The Department for Education and the Home Office take the problems in Birmingham schools and all issues relating to extremism very seriously.
"Michael Gove and Theresa May are working together to ensure we get to the bottom of what has happened in Birmingham and take the necessary steps to fix it."
Three schools inspected over the alleged Trojan Horse plot have been given a clean bill of health by Ofsted.
Ninestiles School - an academy in Acocks Green - Small Heath School and Washwood Heath Academy are the first to publish the results of their inspections after Mr Gove sent Ofsted in. In all, 21 schools have been inspected after a letter, which is widely believed to be a hoax, referred to an alleged plot by hardline Muslims to seize control of governing bodies in the city.
Park View Educational Trust (PVET), which has been the focus of the most damning allegations, issued a statement criticising "leaks" of other unpublished Ofsted findings being reported in the media, stating it was causing "unwarranted and unnecessary concern" for children and parents.
For its part, Park View, which runs three other city schools, has denied any wrong-doing, with trust chairman Tahir Alam calling the allegations "a witch-hunt".
Cooper said: "For two such senior ministers to launch a vitriolic public blame game in this way is appalling and irresponsible when they should be working together to sort out such serious problems.
"Preventing extremism is immensely important - in communities and in schools. The truth is that Michael Gove's reforms have made it easier, not harder, for schools to be run inappropriately, while Theresa May has cut back Prevent programme funding that previously worked to tackle a wide range of extremism."
Hazel Blears, a member of Parliament's Intelligence and Security Committee who had responsibility for the "Prevent" anti-extremism strategy as a Labour minister, said she was "very concerned" that the Government appeared to have scaled back efforts to counter the appeal of militant messages to young Muslims.
Liberal Democrat party president Tim Farron: "My concern is that Ofsted and the local authority in this case ought to be able to move into schools and to take action without fear or favour, and there's a hint from Theresa May's comments that that might not have been the case. That worries me far more than any row between two ministers."
Universities Minister David Willetts did not challenge the suggestion that there was a row but insisted his party colleagues were "highly effective ministers who share a commitment to tackling this challenge".
"What I can say is that in groups such as the extremism task force which the Prime Minister convened last year and which both Theresa and Michael sat on and indeed I participated also myself... actually seeing the workings of Government, I can assure you we were all working together," he told Channel 4 News.
"This is a very serious challenge and it is something you have to tackle at all levels, both with the Home Office responsibility of security and the threat of violence and terrorism and more widely on ensuring people, as they go through our schools and colleges and universities, get some sense of what the values of our society are and we protect them. We are working together on that."
The programme said the Ofsted report into one of the inspected schools - Oldknow Academy - had concluded it was "inadequate" and should be placed in special measures, only just over a year after it was rated "outstanding" in all areas in a scheduled inspection.
Shadow universities minister Liam Byrne, whose constituency includes a number of the schools being examined, said he would not comment on leaked Ofsted findings but said the "botched" process was threatening confidence in the inspectorate's independence.
"These reports should have been published weeks and weeks ago and in the meantime they have been leaked," he told Channel 4. Ofsted's independence, and these are Her Majesty's inspectors, their job is now being compromised by a botched process of school management. The root cause of that has to be traced back to the Department for Education.
"I want Her Majesty's inspectors to be trusted but I'm afraid the way that this whole process has been conducted is destroying confidence in what should be a process of bullet-proof integrity."
An Ofsted spokesman said: "We will be publishing our findings early next week. Ofsted's chief inspector, Sir Michael Wilshaw, had personal oversight of these inspections, which were carried out in very challenging circumstances, and he is completely satisfied that his inspectors conducted themselves with great professionalism and integrity throughout the process."
A Department for Education spokeswoman said: "The allegations made in relation to some schools in Birmingham are very serious and we are investigating all evidence put to us in conjunction with Ofsted, Birmingham City Council and the police. It is absolutely vital these investigations are carried out impartially, without pre-judgment.
"Ofsted has inspected a number of schools in the light of recent allegations and will report to the Secretary of State shortly. Retired senior police officer Peter Clarke has been asked by the Secretary of State to make a full enquiry into Birmingham schools and will report back this summer."