Ministers are to consider whether state school pupils should be allowed to study International GCSEs.
O-levels were phased out 18 years ago
IGCSEs involve less coursework and some consider them to be more challenging and better preparation for A-levels than traditional GCSEs.
Some private schools already teach them but state schools cannot because they only get funding for approved exams.
Schools Minister Lord Adonis' call for a debate has won the backing of former schools inspector, Sir Mike Tomlinson.
State schools have been required to teach pupils GCSEs since they replaced O-levels 18 years ago.
They are not able to enter their pupils for IGCSEs because they only receive funding for approved exams - and these have not been accredited by the regulator, the Qualifications and Curriculum Authority (QCA).
The qualifications are not taken into account in the school league tables.
But the Conservatives and private schools have been urging the government for some time to approve IGCSEs.
Lord Adonis now plans to ask the QCA to publish its research paper on the IGCSE.
He said: "I propose to ask the Qualifications and Curriculum Authority with the agreement of Cambridge Assessment and Edexcel to publish its working paper on the IGCSE so that the government can invite a wider debate within the education community on the IGCSEs use in the maintained sector.
"We will then look at the outcomes of that debate with an open mind."
The paper looked at the structure and content of the IGCSE and how it is taught, the QCA said.
A spokesman said it did not reach any fixed conclusion but, if the government backed its use, accreditation could happen within the year.
Mr Tomlinson, former chief inspector for schools, has carried out a review of the exam system himself and welcomes the government's decision.
He acknowledges there is a pressure to provide a more stretching examination for the most able 16-year-olds, but has some reservations.
"If it is adopted, the risk is you will have a two-tier system - one which values the international GCSE and one the existing GCSE," he said.
Shadow schools minister Nick Gibb said: "It is only right that the International GCSE - which is available for use by the independent sector - should also be available for state schools.
"The IGCSE stretches able pupils, and in the sciences and maths provides a very good foundation for those hoping to study these subjects at A-level and beyond."
Currently, about a third of private schools teach at least one subject at IGCSE.
Independent Schools Council general secretary Jonathan Shephard said it was long overdue that IGCSE results were included in performance tables otherwise some of the most outstanding schools in the country were not being credited.
Cambridge Assessment, one of two boards offering the exam, also welcomed the government's announcement.
Tim Oates, of Cambridge Assessment, said: "The time is right for a fuller discussion of whether all students and schools should be able to access the benefits of these qualifications."