Suicide bombers have struck a mosque in Yemen's capital in an attack targeting Shia worshippers that killed at least 25 people and wounded dozens, medics and witnesses said.

There was no immediate claim of responsibility but Sanaa has been shaken by a string of bombings by the Islamic State of Iraq and the Levant (ISIL) group in recent months targeting Shia Muslims.

Thursday's blast ripped through the Balili mosque where Houthi Shia rebels who control Sanaa go to pray, according to witnesses.

It came as worshippers marked Eid al-Adha, the Feast of the Sacrifice, the most important holiday of the Islamic calendar.

Witnesses reported that after a first blast inside the mosque, a second suicide bomber detonated an explosives belt at the entrance as worshippers rushed outside.

ISIL, a Sunni Muslim group which controls swathes of territory in Iraq and Syria, considers Shias to be heretics.

ISIL bomb attacks targeting several Shia mosques in Sanaa on March 21 killed 142 people. The group has also claimed attacks on mosques in Kuwait and Saudi Arabia.

The capital of Sunni-majority Yemen has been under the control of the Iran-backed Houthi rebels for the past year. The Houthis have also expanded their grip to other parts of the country.

Extremists exploit chaos

Pro-government forces backed by air strikes and troops provided by a Saudi-led Arab coalition have recently managed to wrest back some southern provinces, including the second city of Aden.

After six months in exile in neighbouring Saudi Arabia, President Abd-Rabbu Mansour Hadi returned to Aden on Tuesday with a vow to liberate the country from the Houthis.

The Saudi-led coalition launched air strikes against the rebels on March 26, and began a ground operation in July.

Hadi loyalists began an all-out offensive against the Houthis in the oil-rich Marib province east of Sanaa earlier this month, aiming to retake the capital.

The United Nations says around 5,000 people have been killed and 25,000 wounded, many of them civilians, since late March in Yemen.

Yemen has descended into chaos since the 2012 ouster of longtime strongman Ali Abdullah Saleh, and security has broken down since Houthi militiamen swept unopposed into the capital a year ago.

ISIL and the Yemen-based branch of its rival Al-Qaeda have exploited the turmoil to boost their activities in the impoverished country on the tip of the Arabian Peninsula.

Al-Qaeda has long been a dominant force in Yemen, located next to oil-flush Saudi Arabia and key shipping lanes, but experts say ISIL is seeking to supplant its rival.

Al-Qaeda in the Arabian Peninsula (AQAP) controls parts of the vast southeastern province of Hadramawt, including the provincial capital Mukalla, which it is seized in April.

It has distanced itself from ISIL's tactics, saying that it avoids targeting mosques to protect "innocent Muslims".

Source: AFP And Reuters