Over 7,700 Yemenis were killed over the course of 2014 due to armed clashes, according to a study published by a Yemeni NGO late Saturday.

The study conducted by Abaad Studies and Research Centre noted that the 2014 figures represent a threefold increase from the toll of 2011, when a popular uprising broke out against the country's former president Ali Abdullah Saleh.

Sources for the figures cited in the study were not revealed.

According to the study, the Yemeni military lost more than 1,000 troops during 2014, of which at least 600 were killed by members of the Shiite Houthi militia.

The remaining 400 Yemeni troops were killed mostly by Al-Qaeda militants and other armed groups, the study said.

In terms of civilian casualties, the study estimates that more than 1,200 people were killed during armed clashes in 2014.

The study also claims that over 5,000 Houthis were killed across Yemen in 2014.

Losses within the ranks of Al-Qaeda in Yemen are estimated between 400 and 500, the study said.

For the last several months, Yemen's Shiite Houthi militia – which boasts thousands of diehard supporters – has been trying to step up its armed presence across the fractious country.

The Houthi movement has recently emerged as a political and military power in Yemen after taking over Sanaa and seeking to extend its influence into other provinces.

The Houthis' growing power has pitted the group against Sunnis. 

Houthis kidnap 22 Arhab tribesmen

Meanwhile, Yemeni militants affiliated with the Houthis have kidnapped 22 tribesmen from the northern Arhab region, tribal sources said Monday.

"The Houthi militants kidnapped 22 people from Arhab tribe, including children, in Beit Maran district before taking them to an unknown location," one of the sources told The Anadolu Agency on the condition of anonymity.

The kidnapping came one day after two Houthi militants were killed in the same district in a roadside bombing, he added.

The Houthis have staged an aggressive campaign in Arhab district for several weeks now under the pretext of fighting al-Qaeda.

Last month, the Arhab tribe decided to withdraw its fighters from flashpoint areas in the district that carries the same name in order to avoid clashes with the Houthi militants.

Bombing hits house of Houthi militia leader in Dhamar

A bomb explosion in a mainly Shiite Yemeni city on Sunday killed at least four people and wounded 25 others, officials said.

The bombing targeted a gathering of Shiite Houthi militiamen, also known as Ansarullah, in Dhamar which the group controls, a security official said.

Saba, the official news agency, reported that three members of the "popular committees", a local police force created by the Houthi militia, and a reporter lost their lives in the blast.

The journalist was identified as Khaled al-Washli, who worked for the Houthi-owned Al-Masirah television channel.

Al-Masirah confirmed Washli's death on its Facebook page.

Saba said that members of the popular committees discovered the bomb at one of their buildings in Dhamar but it exploded as they tried to defuse it.

However, a security official in Dhamar told AFP the device had been planted in a vehicle, and gave a toll of six dead and 27 wounded.

This differing account could not be confirmed from other sources.

Later Sunday, Al-Qaeda in the Arabian Peninsula in a statement posted on websites claimed the attack and said it was carried out by a roadside bomb.

The Houthis took over Dhamar, south of Sanaa, where they have the support of the city's mostly Shiite population, but have met fierce resistance elsewhere from Sunnis.

Houthi chief threatens to seize oil-rich province

Meanwhile, the head of Yemen's Shiite Houthi militia threatened Saturday to take control of the oil-rich Marib province, targeted by the group since it seized the capital and central areas three months ago.

"If official authorities do not assume their responsibilities, (we) will act to support the honourable people of Marib," Abdelmalek al-Houthi said in a televised address to supporters in Sanaa. 

Houthi accused "certain" tribesmen of wanting to hand over Marib to al-Qaeda.

On Thursday, Sunni tribesmen ambushed a military convoy travelling between Marib and Sanaa and seized heavy weapons they said were destined for the Houthi militants, tribal sources and witnesses said. 

Three soldiers died during ensuing clashes, according to Yemen's High Security Commission, which demanded late Friday that the tribesmen return the seized equipment.