Yemeni security forces and regime backers on Saturday opened fire on demonstrators in Taez, wounding more than 30 people, one of whom was declared clinically dead, medics and witnesses said.
The Gulf Cooperation Council (GCC) chief, meanwhile, returned to Sanaa in a renewed bid to resolve Yemen's political crisis.
At least 16 people were shot and wounded as police, elite Republican Guard soldiers and armed "thugs" fired at demonstrators in Taez, Yemen's second largest city, medics said.
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Saleh's loyalists also opened fire on demonstrators in Taez earlier the same day, wounding 15 other people, medics and witnesses said. One of the casualties was later declared clinically dead.
Protesters seized three of the assailants who they said were "armed thugs" working for the regime, organisers said.
Tens of thousands had joined a protest march along the city's main thoroughfare, a day after a defiant Saleh rebuffed a call from his longtime US ally to step down "now," according to witnesses.
A general strike called by the opposition took widespread effect on Saturday in Taez and most shops stayed closed in formerly independent southern Yemen, although the strike was less well observed in Sanaa.
The latest tensions simmered as GCC chief Abdullatif al-Zayani flew in to Sanaa in a new attempt to convince rivals to sign a Gulf-brokered plan that would see Saleh out of office within 30 days, political sources said.
The GCC plan, which lost Qatar's support on Thursday, proposes the formation of a government of national unity, Saleh transferring power to his vice president and an end to the deadly protests.
The president would submit his resignation to parliament within 30 days and this would be followed by presidential election within two months. In exchange, Saleh and his top aides would be granted immunity from prosecution.
Parliamentary opposition spokesman Mohammed Qahtan has said the GCC initiative was "dead" following the pullout of Qatar, whose prime minister angered Sanaa by stating the Yemeni president must go.
On Friday, Sanaa was the scene of rival demonstrations by supporters and opponents of the embattled president, who told a loyalist rally: "We will not remain passive in the face of law-breakers."
Republican Guards, who are led by Saleh's son Ahmed, killed at least three anti-government demonstrators in the southern city of Ibb on Friday, opposition sources and witnesses said.
Those deaths brought to 179 the number of people killed in three months of protests against Saleh's regime, according to a toll compiled from reports by activists and medics.
