A registered sex offender given clearance by Education Secretary Ruth Kelly to work as a teacher landed a job in a high school, it has emerged.
But he resigned after teaching for only a few days when police protested.
Ms Kelly had decided not to ban him because she apparently believed evidence he had accessed paedophile websites was inconclusive.
The teacher, who is on the sex offenders register, was given a job at Hewett School in Norwich last month.
Ms Kelly had handed approval for him to work in schools the previous May.
The Department for Education (DfES) wrote to Norfolk County Council saying that she had “considered all aspects of the case, including sex offender registration, and decided that the risks of the teacher being allowed to continue teaching were acceptable”.
The department’s Safeguarding Children Unit said Ms Kelly did not believe he belonged on list 99, the national list of people barred from working with children.
But police reportedly followed strict Home Office guidelines in placing him on the sex offenders register, and have privately expressed deep reservations about her decision.
Norfolk police spokesman Simon Morgan said: “Swift action was taken as soon as this matter came to our attention.
“We convened an urgent meeting with all relevant partner agencies and individuals, including the head teacher, to review the situation and determine the most appropriate course of action.”