Dozens of Yemeni protesters were wounded on Sunday when police used live rounds, tear gas and batons to try to break up demonstrations against President Ali Abdullah Saleh in Taiz, a medical source said.
About 10 people had been hit by live bullets but most were suffering asphyxiation from tear gas, the doctor said.
Saleh had called on opponents demanding he step down to end weeks of street protests on Sunday, in a further sign the veteran ruler has no intention of resigning soon.
"We call on the opposition coalition to end the crisis by ending sit-ins, blocking roads and assassinations, and they should end the state of rebellion in some military units," Saleh told visiting supporters from Taiz province, south of Sanaa.
"We are ready to discuss transferring power, but in peaceful and constitutional framework," he added to chants of "No concessions after today!".
His ruling party also said it had not received a proposed transition plan from opposition parties that envisages Saleh handing power to a vice president while steps are taken towards a national unity government and new elections.
"We haven't got it yet," an official said.
Weeks of protests inspired by uprisings in Egypt and Tunisia have brought Saleh's rule to the verge of collapse, but Saleh, a perennial survivor, has resisted the calls to jump.
He has received sustenance from the United States, which has talked openly of its concern over who might succeed a man they view as an ally who helped them contain al Qaeda in the Arabian Peninsula, a Yemen-based wing of the militant group.
Opposition groups stepped up actions against Saleh in the port city of Aden, seat of a separatist movement by southerners who say the 1994 unification of South Yemen with Saleh's north has left them marginalised.
Much of the city was deserted in a second day of civil disobedience as businesses stopped work. Opposition groups have also called on people to stop paying taxes and utility bills.
Thousands have been camped out around Sanaa University since early February, but in the past two weeks Saleh has begun mobilising thousands of his own supporters on the streets.
On Saturday, seven protesters were wounded in the Western port of Hudaida when riot police used batons and teargas to disperse demonstrators. Protesters said police fired live rounds and tear gas on Sunday to disperse them in Taiz.
SALEH DIGS HEELS IN
Saleh, in power for 32 years, has only said he would be prepared to step down within a year following new parliamentary and presidential elections and that an abrupt exit would cause chaos. On Saturday, he thanked thousands of supporters gathered near the presidential palace for backing the constitution.
"I salute you for your heroic stand and thank you for supporting constitutional legitimacy," he told the crowd amid a sea of his portraits and banners supporting his continued rule.
The opposition plan would see the army and security forces restructured by a vice-president acting as temporary president, a statement from Yemen's opposition coalition said on Saturday.
Wide discussions could then be held on constitutional changes, a unity government and new elections.
Talks have been off and on over the past two weeks, sometimes in the presence of the U.S. ambassador. Sources say Saleh wants to ensure he and his family do not face prosecution over corruption claims that the opposition has talked about.
The death of 52 protesters on March 18, apparently at the hands of government snipers, led to a string of defections among diplomats, tribal leaders and key generals, spurring Saleh to warn against a coup that he says will lead to civil war.
At least 82 people have died so far in the protests.
Key foreign backers like the United States and the oil giant Saudi Arabia are concerned over who would succeed Saleh.
They have long regarded Saleh as a bulwark of stability who can keep al Qaeda from extending its foothold in a country which many see as close to disintegration. Opposition parties say they can handle militants better than Saleh, who they say made deals in the past to avoid provoking Islamists.