Yemen unrest: Deadly clash during protest in Taiz
At least three anti-government protesters have been killed and scores wounded in clashes with security forces in the Yemeni city of Taiz, medics say.
Witnesses said police opened fire on a funeral procession for demonstrators killed last week.
Doctors told the BBC that many people had been affected by tear gas and about 100 had gunshot wounds. Clashes have continued into the night.
Meanwhile, hundreds of thousands attended rival demonstrations in Sanaa.
Addressing his supporters at one rally, President Ali Abdullah Saleh rejected the "belligerent intervention" of Yemen's neighbours, who want to mediate in the dispute.
On Thursday, Qatari Prime Minister Sheikh Hamad Bin Jassem Al Thani said the six-nation Gulf Co-operation Council (GCC) hoped "to reach a deal with the Yemeni president to step down". In return, he and his family would be granted immunity from prosecution.
Mr Saleh said: "Our power comes from the power of our great people, not from Qatar, not from anyone else. This is blatant interference in Yemeni affairs."
He added: "We reject any coup against democracy, the constitution and our freedom... We reject this belligerent intervention."
A BBC correspondent says Mr Saleh's speech was brief but potentially very damaging to any prospect of resolving this crisis peacefully.
Mobile phone footage from Taiz showed chaotic scenes and panic in the streets with the injured being treated in makeshift hospitals.
Peaceful anti-government protests took place in the port city of Aden and also in Hudaida.
Protester Abdullah Fakira said: "We are tired of this poverty and oppression in Hudaida and all of Yemen. Enough already."
Diplomats and government sources in Sanaa say that the president's family members, many of whom hold powerful positions, are putting a lot of pressure on him to stay, our correspondent adds.
Police and army units were deployed in Sanaa to prevent clashes between the two sides. The opposition rally was reportedly larger.
Hammoud al-Hitar, who resigned as minister of religious endowments and guidance last month, told anti-Saleh protesters before Friday prayers that their aim was to "establish a civil state that respects human rights".
The former judge also dismissed the government's claim that al-Qaeda in the Arabian Peninsula (AQAP) would seize control of the state if Mr Saleh stepped down. He said the militant group's presence in Yemen was "less than 10% of what the government media used to portray it".
"The threats against al-Qaeda have been exaggerated by the government media because the officials want to get money in the name of fighting terrorism."
More than 120 people have been killed since Yemenis began calling for the removal of President Saleh after 32 years in power, inspired by the popular uprisings in Tunisia and Egypt.