Further talks to resolve Yemen's political crisis have failed after the deputy to wounded President Ali Abdullah Saleh refused to speak with groups demanding he cede power immediately, opposition figures said.
Saleh, forced to seek medical treatment in Saudi Arabia for wounds suffered in an attack on his palace nine days ago, has withstood nearly six months of street protests and multiple diplomatic attempts to nudge him out of office.
The ensuing political paralysis, and longstanding conflicts with Islamist insurgents, separatists and rebel tribesmen, has fanned Western and regional fears of Yemen collapsing into chaos and giving al Qaeda a foothold astride oil shipping routes.
A member of the group of opposition parties demanding Saleh formally transfer now said international efforts to broker an agreement to that end had collapsed because the acting leader, Vice President Abd-Rabbu Mansour Hadi, would not talk with them.
"The American and European efforts for a dialogue between opposition parties and the ruling party has failed. The vice president has refused to deal with or meet opposition parties," Mohammed al-Mutawakkil said.
"He justifies that by saying he is preoccupied with dealing with the fuel crisis and the ceasefire, as well as the security situation in the provinces."
A ceasefire has held in Sanaa since Saleh left a week ago, after more than 200 people were killed and thousands fled during two weeks in clashes between his loyalists and the forces of tribal leader Sheikh Sadeq al-Ahmar, who backs the protesters.
The capital, however, is all but paralysed by shortages of fuel and electricity and violence in a southern province -- whose capital Islamist gunmen seized last month -- has worsened.
Yemen's army killed 21 al Qaeda members in the southern province of Abyan on Saturday, 18 of them in Zinjibar, the provincial capital that fell. Ten soldiers were killed in fighting there and another city, Lawdar, state media said.
Opposition parties have said they will form their own transitional assembly in a week if Saleh does not cede power. It is not clear whether those parties have any significant influence over many of the protesters.
Saleh has three times backed out of plans crafted by oil-rich Gulf neighbours to quit after a transitional period.
Thousands of people have already fled the clashes between the army and al Qaeda in Abyan. Saleh's opponents have accused him of handing over Zinjibar to Islamists to reinforce his threat that the end of his three-decade rule, as demanded by protesters, would amount to ceding the region to al Qaeda.
Saleh has not been seen in public since the palace attack, which left him with burns and shrapnel wounds. Yemen's ambassador in London said on Saturday that he was recovering and in "stable condition".
Saudi medical sources and Yemeni officials said the Prime Minister Ali Mohammed Megawar and another cabinet member injured in the palace attack had been taken for more surgery, and described their condition as "serious".
A Russian Emergencies Ministry Ilyushin-76 airliner took off on Sunday for Yemen to evacuate any Russian nationals who want to leave the country, Interfax news agency reported, citing a ministry official. About 1,000 Russians citizens are in Yemen.