The Saudi-backed presidential council in Yemen has expelled the leader of a separatist group and charged him with treason after he failed to fly to Riyadh for talks.
Six other members of the presidency accused Aidarous al-Zubaidi, head of the United Arab Emirates-backed Southern Transitional Council (STC), of undermining the independence of the republic.
A Saudi-led military coalition said Zubaidi fled after not joining STC officials on a flight from Aden and moved a large force to al-Dahle province. Coalition aircraft launched strikes on the forces in response, it added.
The STC said the strikes, which reportedly killed four people, were unjustified and that Zubaidi was still in Aden.
It also expressed concern that contact had been lost with the group's delegation in Riyadh.
The past few weeks have seen southern Yemen moving to the brink of a new conflict, pitting factions battling the Iran-backed Houthi movement in the country's decade-long civil war against each other and deepening a rift between Saudi Arabia and the UAE.
STC-aligned forces have in recent years taken control of much of the south, which they want once again to be an independent state, by pushing out forces loyal to the internationally recognised government and the Presidential Leadership Council overseeing it.
In December, the STC's forces launched offensives to seize the eastern provinces of Hadramawt and al-Mahra from the government, saying they were necessary to restore stability in the south and combat the Houthis, al-Qaeda and Islamic State group.
However, Saudi Arabia warned last week that the advances near the kingdom's borders constituted threats to its national security as well as the security and stability of Yemen.
It also accused the UAE of pressuring its separatist allies to push into eastern Yemen and expressed support for a demand from the presidential council for all Emirati forces to leave.
At the same time, the Saudi-led coalition - which was formed in 2015 by Arab states, including the UAE, after the Houthis seized control of north-western Yemen - struck what it said was a shipment of weapons and military vehicles for the STC that had arrived from the UAE.
The UAE expressed deep regret at the Saudi accusations and denied there were any weapons, but agreed to pull its remaining forces out of the country.
Since then, forces loyal to the government have largely retaken control of Hadramawt and al-Mahra with the help of coalition air strikes.
In order to further diffuse tensions, Zubaidi and an STC delegation had been due to fly from Aden to Riyadh on Tuesday night for talks with the government. However, the coalition said the plane left three hours late without Zubaidi, who fled to an unknown location.
Coalition spokesman Maj-Gen Turki al-Malki stated that intelligence indicated Zubaidi moved a large force towards al-Dhale, prompting the coalition to launch pre-emptive strikes.
More than 15 strikes hit al-Dahle early on Wednesday and at least four civilians were killed, two hospital sources told AFP news agency.
Maliki accused Zubaidi of distributing weapons to dozens of elements in Aden with the aim of creating unrest.
Later, the presidential council issued a decree stripping Zubaidi of his membership and referring him to the attorney general for prosecution on charges including high treason.
STC's foreign affairs authority stated it remained committed to political dialogue while condemning the coalition's air strikes as an unfortunate escalation.
They expressed concern regarding communication with their delegation in Riyadh, indicating a climate of uncertainty and escalating tensions in the region.
