Ghana has been ranked last among 76 countries across the world in the latest biggest ever global school rankings on mathematics and science.

Other countries in the lowest ranks are Oman, Morocco, Honduras, South Africa which were ranked 72, 73, 74 and 75 respectively.

Singapore heads the table, followed by Hong Kong, with all other African countries cited in the report at the bottom.

The Organisation for Economic Cooperation and Development (OECD) think tank says the comparisons - based on test scores in 76 countries - show the link between education and economic growth.

"This is the first time we have a truly global scale of the quality of education," said the OECD's education director, Andreas Schleicher.

"The idea is to give more countries, rich and poor, access to comparing themselves against the world's education leaders, to discover their relative strengths and weaknesses, and to see what the long-term economic gains from improved quality in schooling could be for them," he said.

The top performer, Singapore, had high levels of illiteracy into the 1960s, said Mr Schleicher, showing how much progress could be made.

The UK is in 20th place, among higher achieving European countries, with the US in 28th.

The rankings are based on an amalgamation of international assessments, including the OECD's Pisa tests, the TIMSS tests run by US-based academics and TERCE tests in Latin America, putting developed and developing countries on a single scale.

The findings will be formally presented at the World Education Forum in South Korea next week, where the United Nations is to convene a conference on targets for raising global education by 2030.

Below is the full list of countries included in the report