Yemen's southern separatists said on Thursday they were ready to attend a summit in Saudi Arabia to resolve a standoff in Aden after they seized the southern port, seat of Yemen's Saudi-backed government.

The takeover by the United Arab Emirates-backed separatist forces exposed cracks in the Saudi-led military coalition that has been battling the Iran-aligned Houthi group for more than four years and complicated United Nations efforts to end the war.

"We thank Saudi Arabia for its earnest efforts to contain the crisis and invite the parties for talks in Jeddah," the Southern Transitional Council (STC) said in a statement. "The meeting will be held as soon as necessary arrangements are completed."

The separatists are a major component of the alliance that intervened in Yemen in March 2015 against the Houthis after they ousted the government of President Abd-Rabbu Mansour Hadi from power in the capital Sanaa in late 2014. The government rebased in Aden, while Hadi remains in Riyadh.

The war has revived old strains between north and south Yemen, formerly separate countries that united into a single state in 1990.

STC forces took government bases after accusing the Islah party allied to Hadi of being complicit in a Houthi missile attack on southern forces earlier this month, a charge the party denies.

The STC statement outlined its plans for governance in Aden, including "moving all military units to bases outside the city with the exception of public security and support troops."

Hadi's government has said it would not participate in the summit unless STC forces reverse their "coup" and called on the UAE to stop backing them.