The U.N. Security Council has condemned "in the strongest terms" Wednesday's terrorist bombings in Yemen that killed at least 31 people and wounded 20 others, hours before the start of Ramadan, the Muslim holy month.
Three mosques in the capital, Sana'a, were among four targets.
The council said Thursday that any act of terrorism is criminal and unjustifiable, regardless of its motivation. It repeated the need to bring the perpetrators and financiers of terrorism to justice.
The Sunni radical Islamic State group claimed responsibility for the four separate car bombings, calling it Muslim revenge against Yemen's Shi'ite Houthi rebels. The Sunnis regard Shi'ites as heretics.
The Houthis took over Sana'a last year, forcing Yemen's internationally recognized president, Abdu Rabu Mansour Hadi, to flee to Saudi Arabia.
The Islamic State group is starting to make its presence felt more and more inside Yemen, where the Houthis are coming up against numerous militant groups and tribal militias, all jockeying for power.
The fighting and the Saudi-led Arab coalition airstrikes on the Houthis are adding to the misery in Yemen. The U.N. says more than 15 million people lack access to basic health care, and 80 percent of the population is in need of critical humanitarian aid.