Yemen's Houthi militia raid Islah party office

Shiite Houthi militants on Monday raided an office of a Muslim Brotherhood-affiliated political party in Yemeni capital Sanaa, a party source has said.

"Houthi militants ransacked the party's Sanaa office," the source, from Yemen's Brotherhood-affiliated Islah Party, told the Anadolu Agency.

The Houthis stormed the office on Sunday and took four party members to an undisclosed location.

Since it seized Sanaa last September, the Shiite group has confiscated several of the Islah Party's offices in Sanaa and reportedly attacked other offices in other parts of the country.

Houthi leader Abdel-Malek al-Houthi recently accused the party of colluding with Al-Qaeda inside Yemen.

Tension has mounted in Yemen since the Houthis seized Sanaa last September, from which it has since sought to expand its influence farther afield.

On 6 February the Houthis issued a "constitutional declaration" dissolving the elected parliament and establishing a 551-member transitional council.

The declaration was, however, rejected by most of Yemen's political forces – along with some neighbouring Gulf countries – which described it as a "coup against constitutional legitimacy."

Some Gulf States have accused Shiite Iran of backing fractious Yemen's Houthi insurgency.

Hadi 'remains the legitimate president'

Meanwhile, the US envoy to Yemen threw his support Hadi after talks in the southern port city of Aden on Monday, saying he remains the "legitimate" leader.

Ambassador Matthew Tueller was the latest high-profile diplomat to travel to Aden, Hadi's base since he fled effective house arrest in the capital last month following a power grab by the Shiite Houthi militia.

"President Hadi remains the legitimate president of Yemen and the key person to ensure that Yemen moves forward on a peaceful and stable path," Tueller told reporters after meeting Hadi.

A number of countries closed their embassies in Sanaa indefinitely last month and evacuated diplomats and staff due to the worsening security situation.

The Houthis oppose a plan to divide the republic into six federal regions -- a roadmap agreed on during national dialogue stipulated in a peace deal brokered by Gulf neighbours and sponsored by the United Nations.

"The Yemeni people, in electing president Hadi and in participating in the national dialogue conference which he led, have made clear that Yemen's future lies in implementing the GCC (Gulf Cooperation Council) initiative and the national dialogue outcomes," said Tueller.

He warned that "those who are trying to undermine the national conference outcomes or undermine the GCC initiative are seeking to lead Yemen in a very dangerous path."

"We strongly support those who are seeking to lead Yemen to implementation of the national dialogue outcomes," he added.

Yemen has been gripped by unrest since longtime president Ali Abdullah Saleh stepped down in early 2012 after a bloody year-long popular uprising.

Aden has turned into Yemen's de facto political and diplomatic centre since Hadi's arrival. 

The UN envoy to Yemen, Jamal Benomar, also travelled to Aden last week for talks with Hadi aimed at jump-starting reconciliation talks.