Clashes between government troops and al-Qa'ida fighters left 19 people dead in southern Yemen on Wednesday, military officials said.
The fighting is part of an intensified government campaign against the group's strongholds in southern Yemen, where the militants have held a swath of territory, including the provincial capital Zinjibar and several other towns, since last year.
Yemeni forces for the first time are receiving help in the fight from US troops, who are operating from a desert air base near the main battle zones to help coordinate assaults and airstrikes, according to Yemeni officials.
On Tuesday, Yemen's military launched a four-front assault, using warplanes and heavy artillery to clear the way for an assault by ground troops on towns where al-Qa'ida fighters are either operating or in control.
Military officials said tribal militiamen fighting alongside government forces killed 13 militants who had attacked a strategic hilltop, Youssef Mountain, overlooking the town of Lawder in Abyan province. Government forces seized the area a day earlier in heavy fighting.
Two militiamen were killed in the fighting, the officials said on condition of anonymity because they are not authorized to brief the media.
On another front in the provincial capital of Zinjibar, hit-and-run gunbattles between government troops and al-Qa'ida fighters left four soldiers dead, according to a military hospital official.
Also, a security official said a Jordanian surgeon was arrested on suspicion he was heading to Zinjibar to join al-Qa'ida.
All officials were speaking on condition of anonymity because they are not authorized to talk to the media.