Home Secretary Theresa May has insisted she did not authorise the release of an explosive letter to Education Secretary Michael Gove criticising his department's failure to tackle extremism in schools.
Mrs May told the Commons that an inquiry by Cabinet Secretary Sir Jeremy Heywood had cleared her of responsibility for releasing the letter, in the bitter dispute which erupted between the two ministers on the eve of the Queen's Speech.
"As the Cabinet Secretary and Prime Minister concluded, I did not authorise the release of my letter to the Education Secretary," she told MPs.
However she did not respond to a suggestion by Labour shadow home secretary Yvette Cooper that she had deliberately written the letter in order that it could be leaked after learning Mr Gove had launched a fierce attack on the Home Office's record on extremism in a briefing to The Times.
The ensuing row - which totally overshadowed the Queen's Speech - infuriated Prime Minister David Cameron who forced Mr Gove to issue a humiliating apology and Mrs May to get rid of her special adviser, Fiona Cunningham.
Ms Cooper said that the Government's conduct had been "shambolic" and called for assurances from the two ministers that they "will not put their personal reputations and ambitions ahead of making the right decisions for the country".
"Instead of showing leadership and working together, the Education Secretary and Home Secretary chose to let rip at each other in public, making it harder to get the joint sensible working that we need," she said.
Mrs May responded with an attack on the record of the former Labour government, saying that it had actually channelled public funds to groups which supported extremism.
"We make sure that the groups we work with and fund adhere to British values and where they do not we do not fund them and we do not work with them. None of these things was true when the party opposite was in power," she said.
Mr Gove later acknowledged that the Department for Education "may not have acted when it should" in response to warnings of extremism in schools.
He told MPs that he had not been informed of a meeting in 2010 in which a Birmingham headteacher, Tim Boyes, warned that Muslim extremists were trying to take control of schools in the city.
He said that he had now instructed the most senior civil servant in the department - Permanent Secretary Chris Wormald - to carry out an investigation into what had happened.