At least three people have been killed and 39 injured by a bomb explosion at a bus station in Kenya's capital, Nairobi, police have said. The blast happened as passengers passed through a security checkpoint before boarding a coach, which was bound for Kampala in neighbouring Uganda. One of those who died was carrying a bag which contained the bomb, Police Commissioner Matthew Iteere said.

Earlier, Uganda's police chief had warned of attacks by Somali militants. The Islamist group al-Shabab in July said it had carried out twin bomb blasts in the Ugandan capital, Kampala, in retaliation for Uganda's support for Somalia's government.

Most of the wounded were Ugandans travelling home for Christmas, Red Cross official Nelly Muluka said.