The bloodshed in Taiz made clear that a deal to ease President Ali Abdullah Saleh from power has yet to defuse 10 months of violent unrest over the fate of Saleh and the political future of the country.

In Taiz, government forces shot dead three civilians, and a fresh battle between government troops and gunmen backing protesters killed two people trapped in their homes during fighting, protest leaders and medical workers said.

Three government soldiers were killed in what a security source called an attack by fighters tied to the opposition and the Islamic Islah party, which has backed the protests.

Witnesses said street battles with heavy weapons including tanks raged near a police headquarters in the center of Taiz, and activist Tawfiq Al-Shaabi said dozens of families had fled artillery and small arms fire in western areas of the city.

At least 12 civilians, government soldiers and anti-Saleh gunmen were killed in Taiz in the previous few days.

Mohammed Basindwa, a former foreign minister designated by opposition parties to lead a government to be divided between them and Saleh's party, said his side would rethink its commitment to that pact if the killings in Taiz did not cease.

In a statement, Basindwa said the killings in Taiz were "an intentional act to wreck the agreement" that opposition parties signed along with Saleh, who had backed out of signing the deal brokered by Yemen's Gulf neighbors on three previous occasions.