A Kenyan police officer stationed at one of the gates of the president's official residence in the capital, Nairobi, has died after being shot with an arrow, officials have said.

Police said that on Monday morning, a 56-year-old man, armed with a bow and arrows, approached officers at the gate of State House and was ordered to surrender. Instead, he moved forward and shot PC Ramadhan Matanka in the ribs.

The policeman was immediately taken to hospital but died while undergoing treatment, according to a police statement.

The attack has raised questions about possible security lapses as State House is one of Kenya's most heavily guarded locations.

PC Matanka's body is now in a mortuary and there will be a post-mortem later.