Downing Street says the resignation of the Home Secretary's aide Fiona Cunningham follows "unauthorised comments" made to a newspaper during a row over alleged extremism in Birmingham schools.
"In relation to unauthorised comments to the media about the Government's approach to tackling extremism and the improper release of correspondence between Ministers, the Prime Minister has received the Cabinet Secretary's review establishing the facts behind these events.
"In acknowledgement of his role, today, the Secretary of State for Education has written separately to Charles Farr and the Prime Minister apologising for the original comments made to the Times newspaper.
"In addition, in relation to further comments to the Times, Fiona Cunningham has today resigned."
The leaking, from her department, of a letter to Michael Gove, raises serious questions for the Home Secretary to answer.
One school was praised by Ofsted for using money from the pupil premium to pay for a number of cultural trips to Saudi Arabia.
Six Birmingham schools will be rated 'inadequate' and several more downgraded. Council officials have been criticised for failing to act.