Yemeni separatists have taken almost full control of the southern port city of Aden after days of fighting with government forces.
Prime Minister Ahmed Bin Daghar and members of his cabinet are believed to be holed up inside the presidential palace in Aden.
There are reports of talks between the southern separatists and government forces, who were previously allies.
The fighting opens up a new front in Yemen, splitting the alliance against Houthi rebels in the north.
The Red Cross said it has already led to the deaths of 40 people since Sunday.
The separatists are also reported to have also seized Aden’s military bases.
Yemen’s internationally-recognized government relocated to Aden in 2015, when President Abdrabbuh Mansour Hadi and his cabinet were forced to flee the capital, Sanaa, following an offensive by the Houthis.
A assault on Sanaa prompted a Saudi-led multinational coalition to launch a military campaign to defeat the rebels.
According to the UN, since then, more than 9,245 people have been killed and 3 million displaced.