Yemen's southern separatists have seized control of the strategic island of Socotra, which had been in the hands of pro-government forces, and have begun implementing self-rule, officials on both sides said.
The move at the weekend deepens the crisis between separatists and the government after the failure of a power-sharing deal in areas beyond the control of Huthi rebels, who hold the capital Sanaa and much of northern Yemen.
The Southern Transitional Council (STC) declared self-rule in southern Yemen on April 26, accusing the government of failing to carry out its duties and of "conspiring" against their cause.
Senior STC official Salem Abdullah al-Socotri congratulated the separatist forces for "normalising the situation" in Socotra, in a statement issued late Saturday.
A government spokesman said the STC had mounted a "full-fledged coup" on the Indian Ocean island, located near major shipping routes and renowned for its biological diversity.
Its fighters had targeted state institutions and raided military camps and government quarters, he said, according to the official Saba news agency.
He called on the Saudi-led military coalition -- which intervened in the Yemen war in 2015 to support the government against the Iran-backed Huthi rebels -- to stop the STC's "tampering, chaos and attacks" and compel them to implement the power-sharing Riyadh Agreement signed last December.
Socotra's governor, Ramzy Mahrous, said the STC forces "overthrew" state institutions, after which "they raided the city of Hadibou", the island's capital.
Military sources told AFP that the STC took control of the island on Saturday after an operation that began the day before, with only limited clashes with pro-government forces.
STC fighters had entered Hadibou and established checkpoints there, the sources said.