The billionaire philanthropist Bill Gates has delivered a stark warning on population growth in Africa, saying if left unchecked it could unravel decades of progress and fuel instability across the globe.

In an interview with the Telegraph, Mr Gates, who is the second richest man on earth with an estimated wealth of $90bn, described the projected birth rates in the poorest parts of the continent as “mind-blowing” and pressed the need for action.

Praising the prime minister, Theresa May, for her recent pledge to increase British trade and investment in Africa he said the continent was at a turning point.

Either it would reap a population dividend by creating jobs and wealth for its booming population as China and India have done, or insecurity, instability and mass migration could result.

Gates also outlined his three principal global health security concerns: antibiotic resistance, cuts to government funding to improve health in the world’s poorest countries, and the unknown pathogen likely to start the next big pandemic, referred to by the World Health Organization as ‘Disease X’.

“We are not fully prepared for the next global pandemic,” he warned.

Mr Gates spoke to the Telegraph ahead of today’s publication of the Bill & Melinda Gates Foundation’s annual Goalkeepers Data Report, which tracks the greatest challenges faced across the world in terms of poverty and health.