GCSEs are to be replaced with more rigorous O-levels in the most radical overhaul of the school exams system for 30 years, it has been reported.

Education Secretary Michael Gove is set to abolish the national curriculum in English secondary schools according to leaked documents seen by a national newspaper.

The plans are likely to set Mr Gove on a collision course with teaching unions and the Conservatives' Liberal Democrat partners in the coalition.

Under his proposals, pupils would study "explicitly harder" O-levels, covering traditional academic subjects such as English, maths, history, modern languages and the sciences, from September 2014.

Papers would be set by a single examination board to provide a single "gold standard" test across the country with less able pupils sitting simpler examinations similar to the old CSEs.

Mr Gove is said to be preparing to announce his plans formally in the next two weeks before launching a 12-week consultation. None of the changes require legislation.

Labour shadow education secretary Stephen Twigg said Mr Gove must spell out the implications of his proposals to parents.

"To succeed in the modern world, young people need a broad education, not a narrow one. Will pupils doing these new exams get access to creative or innovative learning that will create the jobs of the future?" he said.

A Department for Education spokesman said: "We do not comment on leaks."