Yemen freed at least three suspected Iranian Revolutionary Guard members on Thursday who had been held for months over alleged ties to a Shi’ite Muslim insurgent group that has seized control of much of the capital Sanaa, a senior official said.

The takeover by the Shi’ite Houthi rebels came hours before a power-sharing accord was signed with other political parties providing for the creation of a new government.

That effectively made the Houthis the main power brokers in Yemen, a U.S.-allied country whose political, tribal and sectarian turmoil poses risks to No. 1 oil exporter Saudi Arabia next door. […]