Yemen unrest: Troops fire on Taiz protesters
Yemeni security forces have fired on anti-government protesters, killing at least 15 people and wounding many more, medical sources say.
Witnesses said snipers opened fire from the rooftops when demonstrators reached the governor's offices in Taiz.
Snipers had also reportedly shot at protesters during a march in the fourth-largest city, Hudaida.
The unrest follows weeks of nationwide protests calling for President Ali Abdullah Saleh to stand down.
He has ruled the country for 32 years, but has signalled that he has no plans to leave immediately.
The US has been a key ally of his, but analysts say Washington appears to be losing patience with him.
Countries in the Gulf Co-operation Council regional bloc have offered to host talks between Mr Saleh and opposition groups.
But Mr Saleh has been taking an increasingly hard line with the protesters, and has not publicly responded to offers of mediation.
On Monday, crowds of protesters in the south-western city of Taiz began marching toward Freedom Square - the focal point of protests, where demonstrators have been camping out.
When the march passed the governor's headquarters, troops blocked the procession and clashes broke out.
Activists described chaotic scenes, with live ammunition being fired and military police taking away the bodies of dead protesters.
"It was heavy gunfire from all directions. Some were firing from the rooftop of the governor's building," a witness told the Associated Press.
Hospital sources said at least 15 people had been killed, and 30 more were wounded.
Tanks and armoured vehicles are now blocking entrances to the city and have surrounded Freedom Square, arresting anyone who tries to leave.
The port city of Hudaida saw demonstrators gather in solidarity with people in Taiz and attempt to march on the city's presidential palace.
But police opened fire on them with live ammunition and tear gas leaving dozens injured, witnesses and doctors said.
"They suddenly gathered around the province's administrative building and headed to the presidential palace, but police stopped them by firing gunshots in the air and using tear gas. I saw a lot of plain-clothes police attack them too," an unnamed witness told Reuters news agency.
A BBC correspondent in the country, who cannot be named for security reasons, says President Saleh is under immense pressure.
He has lost allies, the army is split, the government has lost control of entire areas of the country and the economy is collapsing, says our correspondent.
The opposition coalition Common Forum, which includes the five biggest opposition groups in Yemen, has offered a five-point plan for Mr Saleh to hand over power:
- President Saleh resigns and is replaced by Vice-President Abdu Rabu Hadi
- Mr Hadi announces a restructuring of the security forces to make them accountable to the government
- An interim government is created based on national reconciliation
- A new electoral commission is established
- Civil liberties are boosted and an investigation is launched into the killing of protesters
Officials have said they have not yet received a copy of the plan - but speaking at a meeting in Sanaa with representatives from Taiz Province on Sunday, President Saleh called on Common Forum to "end the crisis through calling off protests and removing roadblocks".
Any transition, he said, would have to be made "through constitutional ways".