Gabon’s President Ali Bongo was admitted to hospital on Thursday in the Saudi capital, Riyadh, suffering from “mild fatigue”, a source in the presidency told the magazine Jeune Afrique.

The 59-year-old had been due to appear on a panel at a controversial investment conference in Riyadh on Wednesday, but failed to make an appearance, AFP news agency reports.

Saudi Crown Prince Mohammed bin Salman visited Mr Bongo in hospital on Thursday, AFP quoted the official Saudi Press Agency as saying.

Mr Bongo was sworn in for a second seven-year term in September 2016, after a bitterly disputed election in the oil-rich nation. He took over from his late father Omar Bongo, who had ruled Gabon for 41 years until his death in 2009.