Prime Minister Khaled Bahah's resignation came as the U.N. envoy to the Arab world's poorest country met with representatives from the Shiite rebels, known as Houthis and other political factions to try to implement a deal reached Wednesday to end the crisis.
Under the agreement -- struck while the rebels confined Hadi in his private home -- the group's militias were to withdraw from the presidential palace and key areas of the capital they have overrun in recent days in return for political concessions.
It remains unclear who really controls the country and how much power is still in the hands of Hadi, whose government is viewed as a key U.S. ally in the fight against al-Qaida.
Twenty-four hours after signing the deal, heavily armed Shiite rebels remained stationed outside Hadi's house and the presidential palace.
Bahah's technocratic government was formed in November as part of a United Nations-brokered peace deal after the Houthis overran the capital in September.
Bahah, a political independent, posted his resignation on his official Facebook page, saying he had held office in "very complicated circumstances." He says he resigned in order to "avoid being dragged into an abyss of unconstructive policies based on no law."
"We don't want to be a party to what is happening or will happen," he added.
In an attempt to end the logjam, U.N. Envoy Jamal Benomar arrived to the country and held a meeting with Houthis and other political factions to push for implementation of the deal.
In a brief press conference before the meeting, Benomar told reporters that the deal — in essence an activation of the previous UN-brokered agreement struck in September when Houthis overran the capital — is "the only solution for Yemen."
Yemen's emerging power vacuum has raised fears that the country's dangerous al-Qaida branch, which claimed the recent attack on a French satirical weekly, will only grow more powerful and popular as the nation slides toward fragmentation and the conflict takes on an increasingly sectarian tone. The Shiite Houthis and the Sunni terror group are sworn enemies.
While the capital was free of violence, clashes did erupt southeast of Sanaa between Houthi gunmen and local tribesman. Tribal leaders said two tribesmen and four gunmen allied with Houthi rebels were killed in Khawlan-Watadah, 45 kilometers (30 miles) from Sanaa.
The violence appeared to subside by midday, but a serious flare-up in the region lying along the road to Marib province, an oil-rich area in central Yemen and a haven for al-Qaida fighters, could torpedo peace efforts. At the entrance of Marib itself, clashes also erupted between Houthis and local tribesmen over new checkpoints erected by tribal fighters.
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