The clashes in Abyan and Shabwa provinces are part of a weeks-long offensive against al-Qaida, aiming at uprooting the militant group from large swaths of land the group seized during last years' uprising and the political and security vacuum that followed.
Military officials said that at least six air raids targeted moving vehicles and al-Qaida positions in Mahfad, the last stronghold of al-Qaida in Abyan province. The Yemeni military regained control of several al-Qaida strongholds in Abyan earlier this month.
In another recently recaptured town, Zinjibar, demining teams spotted an Egyptian militant, but he killed himself with a hand grenade before being arrested. Officials said they also found the bodies of seven militants, including three Egyptians, killed in earlier fighting.
To the north of Zinjibar, clashes were still taking place outside Jaar, a town also recaptured by the army earlier last week.
The International Committee of the Red Cross said that one of its workers was killed Wednesday in Abyan province. In a statement, the ICRC said circumstances of the death of the worker, a Yemeni, were not clear.
In Shabwa, militants fled the war in Abyan and sought refuge in the town of Azzan, where the army drove them out to mountainous areas. Three soldiers were killed in the clashes in the two provinces, the officials said. They spoke on condition of anonymity because they were not authorized to speak to reporters.
The Yemeni military's push in the south is supported by US military advisers from a command center manned by dozens of US troops in the al-Annad air base in the southern desert, not far from the main battle zones.
The US considers al-Qaida's Yemen branch, known as Al-Qaida in the Arabian Peninsula, to be the terror network's most dangerous offshoot.
A senior US military official, visiting Yemen on Tuesday, assured officials of the US commitment to support and cooperation in fighting al-Qaida.
General James N. Mattis, commander of U.S. Central Command, met with Yemen President Abed Rabbo Mansour Hadi and senior military officials and reaffirmed the US commitment to a strong partnership, the US Embassy in Sanaa said in a news release.
It said Mattis discussed "ways that the United States can cooperate with the Yemeni military to fight the mutual threat of al-Qaida."
General Mattis informed the Yemeni leaders that "the United States will serve in an advisory capacity as Yemeni leadership restructures the armed forces," and Washington will "stand by Yemen not only through military cooperation, but also in the political, economic, and humanitarian fields as Yemen proceeds with its historic transition."