The Turkish authorities have confirmed that four people were killed and twenty injured by a bomb explosion on board an overnight bus near Kirikkale in central Turkey.

Police suspect that the bomb was planted in the luggage compartment before the bus left the city of Sivas to drive towards Ankara.

The explosion coincided with the twentieth anniversary of the founding of the Kurdish separatist group, the PKK.

A regional governor Behic Celik said the police were also investigating other possible reasons for the attack including a local blood feud or rivalry between bus companies.