Yemen government forces entered the interim capital Aden and recaptured a nearby province Wednesday, officials said, pushing back separatists who had seized parts of the south this month.
"The national army and security services reached at this moment the interim capital and begin to secure districts," Yemeni Information Minister Moammer al-Eryani said on Twitter.
The main gate of the city's airport had also been secured, he added.
An AFP correspondent in the east of the city witnessed shelling by advancing government forces who came fresh from their success in taking back control of Abyan province to the east.
"Heroes of the national army and security agencies have retaken Zinjibar city, the capital of Abyan province, and complete their control over other districts of the province," Eryani said.
A pro-government source told AFP that fighting had erupted in the streets of the city, as loyalist troops fanned out there.
The separatists, who seek an independent South Yemen, seized Aden on August 10 following heavy clashes with government troops. That major gain saw them press on to take other strategic areas, before being pushed back.
Abyan was the second southern province to be retaken by government forces in southern Yemen in days following clashes with the Security Belt, a paramilitary force loyal to the Southern Transitional Council (STC).
Earlier in the week, government forces regained control of Shabwa province after beating back an attack by STC forces.
The new fighting comes despite repeated calls for a ceasefire by the Saudi-led coalition backing the government against Iran-aligned Huthi rebels who captured the capital Sanaa five years ago.
The STC is demanding renewed independence for South Yemen, which was a separate country before unification in 1990.
The fighting in impoverished Yemen has sparked what the United Nations labels the world's worst humanitarian crisis.
Fighters of the UAE-trained Security Belt Force, dominated by fighters of the Southern Transitional Council (STC) which seeks independence, ride atop a tank flying the flag of the former South Yemen in the coastal town of Shuqrah