The local council is now investigating St Luke's college in Bexley, south London, following a revolt by students who accused it of being "more concerned about religion than education" and criticism of teaching standards by inspection agency Ofsted.
Earlier this year, more than 100 teenagers signed a petition protesting over a decision by Maria Williams, the principal, to invite Barbara McGuigan, an American evangelist, to lecture about Christian family values.
It is claimed students were forced to attend a series of talks by the founder of Voice of Virtue International, a Catholic charity, about abortion, sex outside marriage and homosexuality. Last month Mrs Williams suspended 17 students and called them into college for a "re-entry"
interview after they refused to attend Mass.
Campaigners this week said the punishment raised questions about whether students aged over 16 should be forced to attend religious ceremonies.
Collective worship at St Luke's, in line with other state schools and sixth-form colleges, is compulsory.