SANAA (Reuters) - A leader of al Qaeda's wing in Yemen was killed by his brother while praying in a mosque before dawn on Thursday and the brother was then slain in revenge, tribal sources said.
Tareq al-Dahab, brother-in-law of slain U.S.-born cleric Anwar al-Awlaki, was killed with five bodyguards by his brother Hizam and fighters from their Dahab tribe in al-Baydah province.
The killings illustrate the complexity of the security challenges facing Yemen as it prepares for a presidential election to replace the outgoing Ali Abdullah Saleh next week.
"Tareq al-Dahab and five of his bodyguards were killed in a mosque in the al-Manasih area near his home," said a tribal source. "His brother Hizam had three men with him and they killed Tareq and his men easily because they surprised them."
A security source earlier said Tareq was killed at his home.
His loyalists later blew up Hizam's house and killed him in revenge, tribal sources said, sparking a clash between the two brothers' followers. Two of Hizam's supporters were killed in the fighting, bringing the death toll to nine.
Fifteen men were also wounded before a tribal truce calmed the clashes. A third brother, Nabil al-Dahab, is now expected to take Tareq's position as al Qaeda's leader in al-Baydah.
Tareq and his brothers, who have been involved in a two-year struggle for the leadership of the powerful Dahab tribe after their father's death, have each backed different sides as Yemen's complicated political fabric unravelled in 2011.
Tareq, who led an al Qaeda assault on the town of Radda, 170 km (105 miles) southeast of Sanaa last month, was pipped for leadership of the Dahab tribe by his eldest brother Majid, who supported last year's anti-Saleh protests.
Tareq and his brothers had challenged Majid's right to lead tribe.
Yemeni al Qaeda analyst Saeed Abeed said Tareq's death was not a big blow to the group, but could cause a tribal backlash.
"Al Qaeda has lost more important leaders than him, (but) his absence will lead the (Dahab) tribe to take revenge on al Qaeda," Abeed told Reuters.
The Yemen-based al Qaeda in the Arabian Peninsula (AQAP) has emerged as one of the network's most active and ambitious wings after setbacks to al Qaeda groups in Saudi Arabia and Iraq.
Weakened by years of political upheaval, the government has lost control of swathes of Yemen, giving AQAP room to expand its foothold in a country that borders oil giant Saudi Arabia.
Yemenis go to the polls on February 21 to pick a leader to replace Saleh, now in the United Sates for medical treatment, amid concern that violence could reduce voter turnout.
Although he is the sole candidate, Vice President Abd-Rabbu Mansour Hadi needs a large turnout to give him the legitimacy he needs for a two-year interim period in which the armed forces are to be restructured and the constitution overhauled.
Reporting by Mohammed Ghobari; Writing by Nour Merza; Editing by Alistair Lyon