Yemen's separatist Southern Transitional Council (STC) early on Sunday announced it would establish self-rule in regions under their control, which the Saudi-backed government warned would have "catastrophic consequences".
Clashes erupted in southern Yemen on Friday after an explosive device targeted separatist militants, a security source said.
Yemeni government troops took control Saturday of the city of Ataq, two days after deadly clashes between loyalists and southern separatists in the capital of Shabwa province, a pro-government source said.
Southern separatists seized two Yemeni government military bases near the southern port of Aden early on Tuesday, triggering fresh clashes between nominal allies that have complicated UN peace efforts, residents and officials said.
Yemeni separatists have surrounded the presidential palace in the government's interim capital Aden, a military source said Tuesday.