Yemeni government forces in Sana'a have shot and killed at least seven opposition protesters participating in a giant march to the compound of Yemeni President Ali Abdullah Saleh.

Witnesses and medics say Yemeni troops opened fire to stop the march by tens of thousands of anti-government activists who reached Sana'a on Saturday, after a four-day journey from the city of Taiz, 270 kilometers to the south. Thirty or more protesters were wounded. Soldiers and police also fired tear gas and used water cannon to block marchers south of the capital.

Many residents of Sana'a joined the arriving protesters, who want Mr. Saleh to stand trial for the killings of hundreds of activists during the government's efforts to suppress 10 months of opposition demonstrations.

Mr. Saleh has responded to the protests by agreeing to end his 33-year presidency after a February presidential election – a deal backed by Gulf nations and Yemen's ruling and opposition parties. Mr. Saleh also would be granted immunity from prosecution, and the agreement calls for all parties to back his deputy as the sole candidate in the election.

Many activists in Saturday's march chanted, “No immunity for Saleh.”

Meanwhile, Yemeni officials say unidentified gunmen killed British citizen of Yemeni origin and wounded a security officer in a shooting on a vehicle in the southern province of Hadramout on Saturday. One official blamed the attack on highway robbers.