SANAA (Reuters) - Islamic State, an al Qaeda offshoot that has seized large areas of Iraq and Syria, has claimed responsibility for suicide bomb attacks on two mosques used mainly by Shi'ite Muslims in Yemen on Friday, a statement on Twitter showed.

At least 87 people were killed and 260 people were wounded in the blasts in the capital Sanaa. Both mosques are known to be used mainly by supporters of the Shi'ite Muslim Houthi group which has seized control of the government.

(Reporting by Omar Fahmy in Cairo; Writing by Rania El Gamal; Editing by Hugh Lawson)