Yemeni officials say clashes between government forces and separatists backed by the United Arab Emirates have killed at least nine people.
The government and the UAE are part of a Saudi-led coalition that has been battling Iran-aligned rebels since 2015.
But in recent weeks an internal rivalry has boiled over, leading to clashes across the south.
Government forces took control of the southern city of Ataq, the capital of the oil-rich Shabwa province, on Friday.
Sunday's fighting unfolded around 30 kilometers (19 miles) south of Ataq.
The officials, who spoke on condition of anonymity because they were not authorised to brief media, say another 13 people were wounded Sunday.
Ahmed al-Horr, a spokesman for the UAE-backed militia, says it is preparing to attack Ataq after reinforcements arrived from neighbouring provinces.