
At least 13 worshippers have been killed and 45 wounded in an explosion at a mosque in northern Yemen, officials have said.
The blast occured as crowds of people left Friday prayers at the Bin Salman mosque in the Saada region.
There are conflicting reports regarding the cause of the blast.
Some witnesses said a minibus parked outside the mosque exploded, while others said the blast was caused by a booby-trapped motorcycle.
Al Jazeera's Hashem Ahelbarra, reporting from Sanaa, said that many of the dead were members of the Yemeni military.
He said: "This is a very serious development, and the situation remains very delicate."
"Saada is a volatie region, cordoned off by the army - it is essentially off limits, even to local media."
Another Al Jazeera correspondent said the Imam of the mosque was the most likely target of the blast. He is also a military leader in the area.
Huthi denial
Saada province, situated in northwest Yemen, has been the site of a rebellion by members of the Zaidi community, a branch of Shia Islam, that has killed thousands of people since 2004.
The fighters are known as Huthis, named after Hussein Badr Eddin al-Huthi, their former commander, who was killed by the army in September 2004.
However, the group has denied any responsibility for Friday's attack.
Abdul-Malik al-Huthi, brother of the late commander, told Al Jazeera: "We condemn this regrettable incident and deny categorically any role in this incident.
"It is not part of our ethics to target mosques or worshippers at all."
Continued conflict
The renewed violence comes despite efforts to implement a peace deal between the government and the fighters brokered by Qatar in June 2007.
The agreement, under which the fighters would lay down their arms, was revived during a meeting between the two sides in Doha in February.
The Huthis have been fighting to restore the Zaidi imamate, which was overthrown in a coup in 1962.
They reject Ali Abdullah Saleh, the president, and his government although Saleh himself is a Zaidi.