An explosion at a mosque used as a voter center in the eastern Afghan province of Khost on Sunday killed at least 17 people and wounded 34, local officials said, in the latest attack on preparations for long-delayed parliamentary elections.

Basir Bina, spokesman for the provincial police, said people were gathered after afternoon prayers in the mosque, which was also being used as a voter registration centre for parliamentary elections due in October.

He said the blast appeared to have been caused by explosives left in the mosque rather than by a suicide bomber.