The billionaire investor Warren Buffett has donated $1.6bn (£1.05bn; 1.5bn euros) to the charitable foundation created by Microsoft founder Bill Gates and his wife Melinda.

In all, he donated shares worth $1.93bn to five foundations.

The rest went to foundations set up in the name of Mr Buffett's late wife, Susan, and their three children.

Mr Buffett, who owns the investment company Berkshire Hathaway, pledged in 2006 to give away 99% of his wealth.

This year's donation is higher than the figure of $1.5bn donated in 2009 because Berkshire Hathaway has improved its performance.
Largest donation

Mr Buffett is a trustee of the Gates Foundation, which supports projects including polio eradication, micro finance and university scholarships.

The Gates Foundation employs 830 people and spent $3bn (£1.97bn) last year.

The Susan Thompson Buffett Foundation provides scholarships for American college students.

Mr Buffett still holds about $43.9bn of Berkshire stock, or 23.3% of the total outstanding, according to documents filed with the US Securities and Exchange Commission on Friday.

In 2006, Mr Buffett made the largest philanthropic donation in US history, giving $37bn to the Gates Foundation.

In June, he and Mr Gates called on American billionaires to pledge at least half their wealth to charity.

Following their charitable donations, Mr Buffett and Mr Gates are now the world's second and third richest men respectively, behind the Mexican billionaire Carlos Slim.