Plans are being made to scrap GCSEs in 'soft subjects' such as film studies, hospitality and leisure and tourism.
Education Secretary Michael Gove has already toughened up English and maths qualifications, as well as modern languages, history, geography and the sciences.
Exams watchdog Ofqual is now drawing up rigorous guidelines which could call time on 'easier' GCSEs.
An Ofqual spokesman told the Mail: "We're going to be looking at what we think the GCSE should be and what requirements it should have ... exam boards will in future have to meet these requirements.
"If they don't, the subjects won't continue to be GCSEs."
A Department for Education spokesman said: "All GCSEs should be made as rigorous and demanding as the ones we are reforming.
"We are not seeking to axe particular subjects, but they will all have to demonstrate they meet the same high standards if they are to continue."
Ofqual will publish a consultation paper this week on strict new criteria for subjects to attain GCSE status after 2016, calling for more stringent content and assessment.
Many GCSEs could be axed or have to be reclassified as vocational qualifications if they do not meet the standards. It is understood as many as 20 subjects from a list of about 58 GCSEs are under threat.
Tougher GCSEs in English language, English literature and maths are being introduced in 2015, followed by history, geography, the sciences and languages in 2016.
Reformed GCSEs will also be launched that year in art and design, music, drama and dance as well as citizenship, IT, design and technology, PE and religious studies.