This has led to some complaints that African talent is being excluded - though Africans who have attended the listed universities will be able to apply.

The UK scheme will be available to alumni of the top non-UK universities who graduated in the past five years.

Graduates will be eligible regardless of where they were born and will not need a job offer in order to apply.

But the way the list of top global universities has been drawn up has meant that not a single African tertiary institution is listed.

To qualify, a person must have attended a university that appeared in the top 50 of at least two of the Times Higher Education World University Rankings, the Quacquarelli Symonds World University Rankings, or The Academic Ranking of World Universities in the year they graduated.

Thirty-seven universities have made the list - most are in the US, but there are also some in Europe and Asia.

“These ratings are based on criteria that favour universities which have been around for hundreds of years and have access to a lot of funding,” Amina Ahmed El-Imam at the University of Ilorin in Nigeria told the New Scientist magazine.

“As someone from Nigeria who did their PhD in Britain, it’s heartbreaking to see that there are still processes being put in place that inadvertently exclude Africans,” she said.

“Does this visa mean that there are no individual graduates from African universities with high potential?”