Yemeni security guards stand outside the parliament building in Sanna, on February 9, 2015
Sanaa (AFP) - Yemeni political factions resumed UN-brokered talks on Monday aimed at resolving the country's political crisis but one group quickly walked out, underlining the difficult path ahead.
The Nasserite pan-Arab party left the talks saying it had been threatened by a powerful Shiite militia that grabbed power last week.
Saudi Arabia on Monday joined other countries in denouncing the militia, known as Huthis, for carrying out a "coup".
Yemen, which is riven by tribal divisions and awash with weapons, has been engulfed in crisis since veteran strongman Ali Abdullah Saleh was forced from power in 2012 following a bloody year-long uprising against his rule.
The country is also battling an Al-Qaeda insurgency and facing a separatist movement in the formerly independent south.
The crisis escalated after the Huthis last month took control of key government buildings, prompting Western-backed President Abedrabbo Mansour Hadi to tender his resignation.
The Huthis on Friday said they had dissolved parliament and created a "presidential council" to bring the country out of crisis.
UN envoy Jamal Benomar has warned Yemen is at a "crossroads" and urged political leaders to "take up their responsibilities and achieve consensus" as he battles for a negotiated solution.
But as the fresh talks got underway behind closed doors in a Sanaa hotel Monday, the Nasserite party walked out and vowed not to return.
"We will not return to the table of negotiations," Nasserite party chief Abdullah Nooman told reporters.
- Time running out -
He charged that the Huthis were insisting on holding talks based on the "constitutional declaration" under which they took over the government on Friday.
The Huthis have also "threatened to take measures" against the Nasserite party and Al-Islah, a Sunni Islamist party whose supporters have battled the Shiite militia, he added.
The Huthis seized Sanaa in September after sweeping into the capital unopposed from their northern stronghold. Despite a UN-brokered deal, they have refused to withdraw their fighters from the city.
Benomar, who announced the resumption of talks between the Huthis and Yemen's fractured parties on Sunday, has warned that time is running out for a "peaceful solution".
But militia leader Abdel Malek al-Huthi insisted at the weekend that the Huthis would only take part in talks centred on their consitutional declaration, and demanded that their rivals "rectify their policies".
The government takeover by the Huthis has drawn international condemnation, with UN chief Ban Ki-moon calling on Sunday for Hadi to be restored to power.
"The situation is very, very seriously deteriorating, with the Huthis taking power and making this government vacuum. There must be restoration of legitimacy of President Hadi," Ban said.
State news agency Saba, which is under Huthi control, reported that the president had told visitors his resignation is "irrevocable".
Ban also voiced concern that Saleh, considered an ally of the Huthis, had "been undermining the transition process" in Yemen, although Saleh's party has been among those denouncing the militia's actions.
The Huthis have said they will set up a national council of 551 members to replace the legislature as well as a five-member presidential council that would form a transitional government to run Yemen for two years.
They have set up a security commission to run affairs until the presidential council is formed.
The fall of Hadi's government has sparked fears that impoverished Yemen -- strategically located next to oil-rich Saudi Arabia and on the key shipping route from the Suez Canal to the Gulf -- could plunge into chaos.
The Saudi government, in a statement Monday, said the Huthi initiative was akin "to a coup against legitimate authorities".
France meanwhile called on Yemeni politicians to quickly reach a "consensual solution to put end the crisis and push ahead with transition".