Suicide bombers in the Yemeni capital Sanaa have blown themselves up during noon prayers at two mosques used mainly by Shi'ite Muslims, killing at least 87 people and wounding hundreds.

The attacks represent a major escalation of the worst wave of violence in the country in years. Four bombers wearing explosive belts targeted worshippers in and outside the crowded mosques a day after an unidentified warplane attacked the presidential palace in the southern city of Aden.

Anti-aircraft guns also opened fire on planes flying high over the presidential compound in Aden yesterday.

Islamic State, which has seized large areas of Iraq and Syria, claimed responsibility for the mosque attacks.

Yemen is torn by a power struggle between the Iranian-backed Houthi rebels in the north and UN-recognised President Abd-Rabbu Mansour Hadi, who has set up a rival seat in the south with the backing of Sunni-led Gulf Arab states.

The mosques in Sanaa are known to be used mainly by supporters of the Shi'ite Muslim Houthi group, which controls most of northern Yemen, including Sanaa.

The rise to power of the Houthis since September last year has deepened divisions in Yemen's complex web of political and religious allegiances, and left the country increasingly cut off from the outside world.

One witness said he heard two successive blasts at one of the mosques, known as the Badr mosque, in a busy neighbourhood in central Sanaa.

Hospitals in Sanaa appealed for blood donors to help treat the large number of casualties.

Witnesses at the scene of the Badr mosque saw bodies lying in the street and inside the mosque building, with one man carrying a dead child in his arms.

A third suicide bomber tried to blow himself up in one of the main mosques in the northern Houthi stronghold of Sadaa province but the bomb went off prematurely, killing the bomber.

Tensions have risen since Mr Hadi fled to Aden in February after escaping a month of house arrest in Sanaa by Houthi forces in control of the capital.

Mr Hadi has been trying to consolidate his hold over Aden, the better to mount a challenge to the Houthis' ambitions to control the whole country.

Thirteen people were killed on Thursday when forces loyal to Mr Hadi fought their way into Aden's international airport and wrested an adjacent military base from a renegade officer, Aden governor Abdulaziz bin Habtoor said.

Both the fighting on the ground and subsequent air attack appeared to be part of a deepening power struggle between Mr Hadi and the Houthi group, which is allied with former president Ali Abdullah Saleh, a fierce critic of Mr Hadi.

Yesterday a cautious calm returned to Aden as the Yemeni president appeared to be consolidating his control over the city.

The airport reopened and flights resumed.