Yemen's powerful Republican Guard forces opened fire with guns, tear gas and water cannons today at a march by more than 100,000 protesters demanding that the outgoing president be put on trial.
The protesters were attacked as they entered the capital Sanaa after marching for four days from Taiz, a city that has been a major opposition centre 170 miles to the south.
The protest was called the March of Life and aimed to put pressure on the country's new government not to grant Ali Abdullah Saleh immunity from prosecution.
The violence underlined the continuing turmoil in Yemen even after Saleh signed a US and Saudi-backed deal last month by which he handed his powers to his vice president and committed to step down completely in return for immunity.
Protesters who rallied by the thousands for the past nine months rejected the deal, demanding Saleh be tried for his bloody crackdown on their movement.
At the same time, Saleh has seemed to continue to exercise influence through his relatives and loyalists still in their positions, even after Vice President Abed Rabbo Mansour Hadi formed a unity government between the opposition and ruling party. Forces loyal to Saleh have defied orders to withdraw from the streets of Sanaa after a deadline was reached to do so.
The marchers were met today by a force from the Republican Guard, which is commanded by Saleh's son, and Central Security forces, led by Saleh's nephew, backed by tanks on the southern entrance to Sanaa, witnesses said. Troops fired to disperse the crowd, who responded by throwing stones.
One of the march organisers, Abdel Nasser al-Kamali, said 30 people were injured. Injured protesters were taken by motorcycles to nearby clinics, according to activist Samer al-Makhalafi.
As clashes went on, thousands of protesters camping in Sanaa's Change Square, which is the epicentre of Yemen's protest movement, marched to the scene to join in. Witnesses said they saw tanks and artillery units from military camps around the capital also heading to the site.
The march came as Yemen's parliament convened for the first time since opposition and independent lawmakers suspended their participation in March to protest against the crackdown against demonstrators. Lawmakers were to discuss the programme of the new national unity government, headed by veteran independent politician Mohammed Basindwa.
On December 7, Mr Basindwa said the government will focus on providing public services to the people, including electricity, water, fuel and basic commodities together with restoring security and stability.
Services and security have been in short supply during the unrest in Yemen, the poorest country in the Arab world.
However, the presence in the country of Saleh, his sons, family members and loyalists who still hold key positions, could pose a challenge to the new administration.