MAIDUGURI, Nigeria (AFP) - A suicide bomber killed at least nine people on Saturday inside a mosque in northeast Nigeria's city of Maiduguri, with the blast leaving much of the building destroyed by fire, witnesses said.

"It was suicide attack by a bomber who pretended to be worshipper," said Haruna Dawud, a trader at the Monday Market, which is next to the mosque and has been repeatedly attacked by Boko Haram.

Dawud said he saw 20 bodies being evacuated but could not confirm how many were dead. Another trader, Nura Khalid, said he personally counted nine corpses being taken out of the mosque.