|Anti-Saleh protesters took to the streets of Sanaa to show their opposition to the president [Luke Somers]
Yemeni government forces have clashed with supporters of the powerful Hashid tribal grouping led by Sadiq al-Ahmar that is demanding President Ali Abdullah Saleh leave office.
Loud explosions and gunfire rocked the Al-Hassaba district of Sanaa on Friday. Witnesses said an armoured vehicle of the elite Republican Guard, which is led by Saleh's son, Ahmed, was hit by a projectile and set ablaze.
The fighting erupted late on Friday afternoon and lasted about half an hour. Residents reported hearing the crackle of machine-gun fire and a few explosions. There were no immediate casualty figures available.
The troops had earlier blocked several roads and erected checkpoints, triggering a similar action by tribesmen armed with machine guns and rocket-propelled grenades.
In March, Al-Ahmar ended his support for Saleh - also a member of the Hashid tribe - and joined the protests which had erupted in January demanding the ouster of the president.
Last week, influential tribal leaders formed a coalition headed by al-Ahmar to bolster the uprising against Saleh, who has been in a Saudi hospital since June after being wounded in a bomb attack on his Sanaa compound.
Saleh is clinging to power despite being attacked and has vowed to return to Yemen.