Saudi Arabia has accused the United Arab Emirates of secretly helping a wanted Yemeni separatist leader flee the country, deepening an already serious rift between the two Gulf allies over Yemen.

In a statement Thursday, the Saudi military alleged that Aidarous al-Zubaidi, head of Yemen’s Southern Transitional Council (STC), escaped by boat to Somalia before being flown to Abu Dhabi by Emirati officials. Saudi Arabia recently expelled al-Zubaidi from Yemen’s Presidential Leadership Council and charged him with treason, accusing him of undermining unity and pushing for southern secession.

The UAE, a key backer of the STC, did not immediately respond. The STC previously said al-Zubaidi remained in Aden.

In an unusually direct move, the Saudi statement named a senior Emirati officer allegedly involved and claimed the aircraft used had operated in other conflict zones, echoing past Saudi accusations that the UAE funneled arms through the region, claims Abu Dhabi has denied.

Saudi officials said talks were underway with STC representatives in Riyadh to defuse tensions and preserve stability in southern Yemen. The dispute comes amid renewed Saudi airstrikes against separatist forces and risks further destabilizing Yemen, where a decade-long war has killed more than 150,000 people and fueled one of the world’s worst humanitarian crises.