Bill Gates has said there will be “almost no poor countries by 2035”, and that child mortality rates in the poorest nations will plummet to the same levels as in the US and UK in 1980.

The world’s richest man made the prediction in the Gates Foundation’s annual letter, in which he and his wife Melinda Gates sought to dispel three common “myths” surrounding the issues of world poverty.

The foundation, which is expected to have given away the entire Gates fortune of around $67 billion (£40 billion) by the time the couple have been dead for 20 years, has published a letter for each of the last five years detailing global philanthropic progress.

Speaking to Forbes Magazine’s editor Randall Lane, Gates said there will soon come a point where “you’ll have to give a reason why a country is poor.” He said that while it is difficult to make predictions for nations where politics hinders progress (naming North Korea as an example), for almost everyone else there are “good examples to learn from”.

Tackling the first myth, Gates wrote: “Poor countries are not doomed to stay poor. I am optimistic enough about this that I am willing to make a prediction. By 2035, there will be almost no poor countries left in the world. Almost all countries will be what we now call lower-middle income or richer.”

“It will be a remarkable achievement. When I was born, most countries in the world were poor. In the next two decades, desperately poor countries will become the exception rather than the rule. Billions of people will have been lifted out of extreme poverty. The idea that this will happen within my lifetime is simply amazing to me.”