the separatists, who sought self-rule in the south, turned on the government in August last year and seized the interim capital of Aden. The fighting stopped when the two groups reached a deal in November.
Under the accord reached in Saudi Arabia's capital, Riyadh, the STC and other regions in the south were supposed to join a new national cabinet and place all forces under the control of the internationally recognised government.
Mohammed al-Hadhrami, Yemen's foreign minister, said the STC's latest move amounted to a withdrawal from the Riyadh agreement.