Violence has broken out for a third day in Yemen, with government forces reported to have shelled an opposition protest camp in the capital, Sanaa, killing two people.
More than 50 people have been killed in clashes over the past two days between opponents of President Ali Abdullah Saleh and forces loyal to him.
Reports from inside the country suggest a full-blown confrontation is under way. The latest reports speak of heavy shelling and machine-gun fire.
Early on Monday, opposition leaders used loudspeakers to rouse their supporters to more protests.
Witnesses reported that snipers in Sanaa fired from rooftops at a demonstration, killing bystanders including a child.
The Government strongly denied its forces fired on peaceful demonstrators. A Yemeni minister told the BBC that government forces were being attacked by militants sympathetic to al-Qaeda.
Opposition protesters have apparently overrun a major government base with little resistance.
For months, thousands of people have been waging a campaign to depose Mr Saleh, who has ruled the country since 1978 and is currently in Saudi Arabia recovering from a bomb attack in June.
Envoys from the Gulf Cooperation Council and the United Nations have arrived in Sanaa.