Sporadic gunbattles are increasingly turning parts of the Yemeni capital, Sanaa, into a warzone.
Hundreds have been fleeing the fighting between loyalists and opponents of President Ali Abdullah Saleh, who has ruled out any more concessions to those who want to force him from power.
It is the third consecutive day of fierce fighting in which at least 39 people have died. Clashes have been fiercest in the sandbagged streets around the mansion of an influential tribal leader who has backed protesters. Tensions have increased also since the president refused at the last minute to sign a Gulf-brokered deal to ease him out of power.
Saleh insists the agreement remained on the table and that he is ready to sign but he also warned foreign powers not to interfere with what he called an internal affair. Nonetheless, Britain has renewed international calls for Saleh to agree the deal amid fading hopes of a peaceful outcome.