At least 137 people were killed in three bombing attacks in Yemen's capital Sanaa and in Saada province during Friday prayers, with the Islamic State (IS) Sunni radical group claiming responsibility.
"Five IS soldiers wearing explosive vests launched a suicide operation in Yemen. Four of them went to two Shia Houthi headquarters in the mosques of Badr and Hashoush in the capital Sanaa. The fifth soldier went to Houthi stronghold of Saada," Xinhua news agency quoted the IS media office in Yemen as saying in an online statement.
The IS also vowed to launch more attacks against the Houthi group.
The Houthi-run al-Maseera TV reported that a total of 137 people were killed and 350 people wounded in Sanaa and Saada. However, the interior ministry said at least 120 people were killed in the four bombing attacks.
In Sanaa, the bombers detonated explosives at two mosques controlled by the Shia Houthi group, killing at least 119 people, a security official said on condition of anonymity, adding that most of the dead were supporters of the Houthi group.
The first attack hit prayers inside the Badr mosque in southeastern Sanaa, while the second bombing occurred at a checkpoint outside the Hashoush mosque in the city's northeast, he said.
The Houthi-run al-Maseera TV reported that Murtada al-Mahadwari, a prominent Shia religious leader who is also the chief of Badr mosque and its religious centre, was among the dead.
Futhermore, two Houthi commanders were killed in the blast in the Hashoush mosque.
The group also called on Sanaa citizens to donate blood at hospitals as the number of the wounded rose sharply.
Medics said the toll is likely to rise as many people were in critical condition.
This is the second bombing attack in Sanaa this year after an Al Qaeda car bombing attack against a police academy killed at least 50 cadets on January 7.
In Saada province, at least 18 people, most of them Houthi followers, were killed during Friday prayers when a suicide bomber blew himself up at a mosque in Saada city, the provincial capital, he added.
Dozens of people were wounded in the two separate attacks, the source added.
It is the first time that IS launched attacks in Yemen which is on the brink of civil war after years of conflicts.
The Al Qaeda group based in Yemen's southern regions launched a suicide bombing attack against a Houthi gathering on October 9, 2014, killing at least 32 Houthi followers and wounding dozens. It also claimed responsibility on Thursday for the assassination of a senior Houthi official in Sanaa last week.
A small branch of Al Qaeda in the Arabian Penisula split from the network and joined the IS three months ago. The IS statement said this branch carried out these bombing attacks in Sanaa and Saada.
The Shia Houthi group took over control of Sanaa in September and met strong resistance in the central and southern regions from powerful Sunni tribes and the Sunni-dominated Al Qaeda network.
In January, the Houthi group seized the presidential palace in Sanaa and put President Abd-Rabbu Mansour Hadi and Prime Minister Khaled Bahah under house arrest after they submitted resignations.
On February 6, the Houthi group disclosed a unilateral "constitutional declaration" that dissolved parliament and established a presidential council to replace the presidency.
The unilateral move was rejected by Yemen's political parties and denounced by the Gulf Arab states. More than a dozen countries closed their embassies in Sanaa in protest against the Houthi takeover of Sanaa and for security concerns.
Saudi Arabia and the United Arab Emirates have moved their embassies to Aden to show support to Hadi who fled to the southern port city in late February where he resumed presidential duties.
The Shia Houthi group, also known as Ansarullah, is based in the far northern province of Saada. It extended its influence southward after signing a UN-sponsored peace and power-sharing deal on September 21, 2014, following week-long deadly clashes.
Discontented by marginalisation for years, the group battled the government between 2004 and 2010.
Obsevers say that the country may slip into civil war as the south strongly resists the Houthi group that controls four northern provinces including the capital.
The security vacuum could also benefit the al-Qaida in the Arabian Penisula, the most active Al Qaeda group in the region which is considered a major threat to oil-rich Saudi Arabia and the US.
