Yemeni troops have killed at least 13 suspected al-Qaeda fighters, including a local leader, according to the country's defence ministry and the army.
At least four other people, including three soldiers and a tribal chief, Sheikh Abdallah Salem al-Abdelli, were also killed in Thursday's gun battle.
Six of the suspected al-Qaeda fighters, travelling in three vehicles, were killed in an assault in the southern Shabwa province towns of Maifaa and Azzan, the ministry's 26sep.net news website reported.
Troops also killed a local al-Qaeda in the Arabian Peninsula [AQAP] leader, Abu Muslim al-Uzbeki, in neighbouring Abyan province, according to the state news agency, Saba.
The leader "was probably killed in clashes that erupted when army forces advanced into al-Mahfad", an army officer told the AFP news agency, referring to an al-Qaeda stronghold in Abyan.
Uzbeki travelled from Uzbekistan to Yemen in 2011 and was named an AQAP leader in Abyan, according to a security official.
Yemen's army launched a major offensive on Tuesday in an attempt to push the group's fighters from their strongholds in smaller towns like Shabwa and Abyan.
The operation experienced setbacks in the beginning when al-Qaeda ambushed a convoy, killing 15 soldiers and taking 15 others as hostages.
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A total of 21 soldiers and 22 suspected fighters have been reported killed in the ground offensive, which followed intense US and Yemeni air strikes last week.
The US considers AQAP, a merger of the network's Yemeni and Saudi branches, to be one of the most dangerous franchises of al-Qaeda.
Fighters took advantage of a 2011 uprising that forced veteran strongman Ali Abdullah Saleh from power to seize large swaths of southern and eastern Yemen.
The army recaptured several major towns in 2012, but has struggled to reassert control over rural areas.
At least three other people, including three soldiers and a trible chief, Sheikh Abdallah Salem al-Abdelli, were also killed in Thursday's gun battle.
The ambush targeted Baida governor, Aldhaher al-Shadadi, and Ali Mohsen Muthanna, an army regional commander, both of whom escaped unscathed, a military source told AFP.