The Islamic State's branch in Yemen claimed responsibility for an attack on a Shia mosque in the capital, Sanaa, that killed at least 25 people and wounded dozens, according to medics and witnesses.
Dozens of "rejectionists" were killed or wounded in the twin suicide bombing, the Sunni militant group said in the statement.
The group uses the term "rejectionist" to describe Shia Muslims, who it sees as heretics.
The bombing at the al-Balili mosque, run by Yemen's Houthi group just outside the Old City of Sanaa, was the latest in a string of a string of bombings by IS against Shia Muslims.
It came two days after Yemen's president Abdrabbuh Mansour Hadi returned to the southern city of Aden from exile in Saudi Arabia.
Hadi had fled in March following gains by the Iran-backed Houthi rebels, who have since been targeted by a Saudi-led coalition trying to restore Hadi to power and drive the Houthis back to their northern stronghold.
Over 4,500 people have been killed in the conflict, which IS exploited to expand its operations. Shia Houthi rebels still control the capital, however.
On 2 September, twin suicide blasts killed at least 28 people and injured 72 at claimed by a mosque in northern Sanaa while 137 worshippers died in coordinated IS attacks at two mosques during Friday prayers in Sanaa.
