Forty mentally-ill patients have escaped from Kenya's biggest psychiatric hospital.

The inmates overpowered guards at the Mathari Mental hospital in Nairobi before escaping yesterday.

Some of the patients are said to be violent according to police.

A Kenyan newspaper claimed that the patients staged a protest before escaping, after complaining about the standard of medication they were receiving.

The hospital was at the centre of allegations regarding human rights abuses two years ago.