Rival protests stoked up tension in Yemeni capital Sanaa on Sunday as a presidential negotiating team abandoned talks with Shiite rebels, accusing them of seeking to ignite a war.
President Abdrabuh Mansur Hadi urged "vigilance and increased preparation to face any options that could be imposed" on Yemen, at a meeting with the supreme security and military committee, state news agency Saba reported.
Pro and anti-government protest leaders used loud hailers to stir up their followers at rallies in different parts of Sanaa, although there were no clashes between the groups, as had been feared.
Thousands joined the rebel demonstration in the north of the city, near the interior ministry and other government offices, but tens of thousands gathered in central Sanaa to support Hadi's government, an AFP correspondent reported.
Hadi's envoys had held talks with rebel commander Abdulmalik al-Huthi since Thursday in a bid to persuade him to abandon protests organised by his supporters to demand the resignation of the government and reversal of fuel price increases.
But the presidential team's spokesman, Abdulmalek al-Mikhlafi, said the negotiations in Saada, the rebels' stronghold in the mountains of the far north, had failed.
The rebels "rejected all the proposals presented to them," said Mikhlafi.
"It seems like the Huthis want a war," he added, referring to the Shiite rebels, also known as Ansarullah or Zaidi, who have been fighting government troops in the northern mountains on and off since 2004.
- Conflicting slogans -
At Sunday's rallies in Sanaa, rebels followers chanted: "The people want the government out" while five kilometres (three miles) away the slogans from Hadi's supporters predicted the failure of the rebellion.
"Oh, Huthi, Sanaa will be your tomb" and "Huthi is God's enemy" the crowds jeered.
Tens of thousands of armed rebels have set up fortified protest camps around the capital over the past week to press their demands.
One encampment is located in Sanaa's northern district on a road leading to the airport.
Mikhlafi told reporters on Saturday that his team had handed Huthi a draft proposal to form a technocrat government within a one-month period from the date of signing the accord.
Huthi spokesman Mohammed Abdulsalam, however, pinned the blame on authorities, saying the presidential team "had no powers" to guarantee his group's demands.
Apart from revoking the fuel price hikes and the government's resignation, the demands include "a partnership in all the state structures", he said.
Authorities in Sanaa had already stepped up security around vital installations and government buildings including the airport and the interior ministry.
"We are living in constant fear of the situation deteriorating and of a scenario similar to what happened in Amran," activist Amal al-Yafie told AFP.
She was referring to the northern city which the Shiite rebels seized after deadly battles in July, before they later agreed to withdraw.
Yemeni activist Tawakkol Karman, Nobel Peace laureate in 2011, criticised the rebels' use of "violence to achieve political ends".
She told AFP she took part in Sunday's anti-rebel demonstration to "defend the republic and reject violence".
Karman, a member of Islamist party Al-Islah, a Sunni bloc and rival to Ansarullah, slammed the "armed" rebels "who are surrounding the capital and carrying out sit-ins in the city."
Analysts said the rebels are seeking to establish themselves as the dominant force in Yemen's northern highlands and to secure a larger share of power in a future federal government.
April Longley Alley, a Yemen specialist with the International Crisis Group, said that the protests were complicating the negotiations.
"There is still room to find a negotiated settlement, but escalating the protests will likely make finding one more difficult," Alley told AFP.
The Zaidi Shiites, a minority in mainly Sunni Yemen, form the majority in the northern highlands, including the Saada region.
Their protest action has raised fears of new violence in Yemen, which already faces an Al-Qaeda insurgency and a campaign for renewed independence for the south.
The impoverished country has been locked in a protracted transition since long-time strongman Ali Abdullah Saleh was forced from power in February 2012 after a deadly 11-month uprising.
Plans for a six-region federation have been rejected by both the Huthis and the southern separatists.