ADEN  - Three Yemeni soldiers were killed and six others wounded in a roadside bombing that targeted the convoy of a security chief in the southeastern city of Mukalla on Sunday, a security official and witnesses said. The bomb went off as a three-vehicle convoy passed through the Huwaysh neighbourhood of the coastal city, witnesses said. It targeted the convoy of Colonel Abdulwahab al-Waeli, head of Central Security in the city, the security official said.  It was not clear who was behind the attack but Al-Qaeda remains active in the south and east of impoverished Yemen. Al-Qaeda loyalists have carried out a spate of deadly attacks against security forces and their militia allies since President Abdrabuh Mansur Hadi came to power earlier this year pledging to crush the militants.Al-Qaeda took advantage of a nearly year-long uprising against Hadi's predecessor, veteran strongman Ali Abdullah Saleh, to seize large swathes of the south and east.In an all-out offensive launched in May, the army retook a string of towns in Abyan province, which neighbours Aden to the east.