It was the second attack this month on a mosque in northern Yemen.

On May 2, a booby trapped motorcycle exploded outside a Shia mosque in the northern town of Saadah, near the Saudi border, as worshippers were leaving, killing 18.

Northern rebellion

That area in northern Yemen is the site of a rebellion by Shia Muslims of the al-Zaydi sect that erupted in 2004 and has since killed thousands. It is not immediately clear if the Amran attack was connected.

Meanwhile, the area's tribal leaders who asked not to be identified by name because they feared government reprisal, dismissed the claim that the attacker was mentally ill. They said he was a 32-year-old man who works as a driver for a legislator in the area.

In a separate incident, a police official said that two Katyusha rockets were fired at an oil refinery in the Yemeni port of Aden but there was no word of causalities.

An official blamed the attack on al-Qaeda.