India, Jan. 8 -- A council fighting against Yemen's Houthi rebels said on Wednesday that it had expelled the leader of a separatist movement and charged him with treason after he reportedly declined to travel to Saudi Arabia for talks.

The Statement, carried by the SABA news agency affiliated with the anti-Houthi forces, marks a new escalation between Saudi-backed forces and the Southern Transitional Council, or STC, which had been backed by the United Arab Emirates. The rift deepens uncertainty over Yemen's future, already strained by more than a decade of war in the Arab world's poorest country.

An STC delegation that flew to Riyadh was scheduled to attend a meeting to discuss the situation in the southern governorates, but the STC sa...