Birmingham City Council is investigating allegations that a group of radical Muslims is trying to oust head teachers and secretly turn schools into Muslim academies based on Salafi Islam principles, British media reported.

A letter passed to Birmingham City Council outlines a plan dubbed 'Operation Trojan Horse,' aimed at taking over at least four schools in areas of the city with large Muslim populations

In the plan, hardline parents were to rebel against head teachers; they would claim the schools were corrupting their children "with sex education, teaching them about homosexuals, making their children pray Christian prayers and mixed swimming and sports," the Guardian reported.

Allegedly written from one Islamic fundamentalist to another, the letter says the operation is part of a long-term plan and that a number of schools in Birmingham have already been "taken over" in this way.

"Whilst sometimes the practices we use may not seem the correct way to do things you must remember that this is say jihad and as such using all measures possible to win the war is acceptable," the letter is quoted as stating.

However, Tahir Alam – a former chairman of the education committee of the Muslim Council of Britain, who is accused of being one of the plotters – told the Guardian that the letter was "a malicious fabrication and completely untrue."

The police also said that it was not a matter for them and decided not to open an investigation.

READ MORE: ‘Trojan horse’: Radical group ‘aims to convert’ UK schools to strict Islam