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 against each other and deepening a rift between Saudi Arabia and the UAE. STC-aligned forces have taken control of much of the south. In December, the STC's forces launched offensives to seize the eastern provinces of Hadramawt and al-Mahra from the government, defending their actions as necessary for stability. Saudi Arabia warned that these advances constituted threats to its national security. The coalition and the legitimate Yemeni government accused Zubaidi of escalating tensions, leading to military strikes against his forces and a declaration of treason against him. The STC condemned the coalition actions as inconsistent with peace dialogues.