Fresh fighting has flared¹ in Yemen between tribesmen loyal to President Ali Abdullah Saleh and soldiers backing anti-government protesters.

也门总统萨利赫的追随者与反政府抗议者领导的军队发生暴力冲突。

At least three people were killed and 15 others injured in Sanaa after pro-Saleh tribesmen arrived at a barracks occupied by mutinous²（暴动的） troops.

There has also been renewed violence in the city of Taiz, where at least 15 people died on Monday.

The European Union has said that a transition of power must begin now.

More than 100 have died since protests against Mr Saleh began in February.

Protesters are calling for the president to step aside（避开） after 32 years in power, but he has signalled he has no plans to leave immediately.

A BBC correspondent in Sanaa says the number of protesters there is growing and they have erected³ tents in the road leading to the president's official home, about 13km (eight miles) away.

In Taiz our correspondent says gunmen in plain clothes have been seen firing from rooftops towards protesters in the city's Tahrir Square.

A doctor in Taiz told BBC Arabic that dozens of injured protesters had arrived at the hospital with gunshot injuries.

"Others [have been] attacked by bricks," he added.

Taiz was the scene of a deadly crackdown on Monday, where demonstrators calling on Mr Saleh to step down were shot by security forces.

The exact cause of Tuesday's shooting in Sanaa was not clear.

However, reports said a convoy⁴ of vehicles carrying members of the Sanhan tribe - some of whom remain loyal to the president - arrived at the headquarters of the rebellious⁵ army division.

AP news agency, citing security sources, said the visit was an attempt to negotiate with Maj Gen Ali Mohsen al-Ahmar, commander of the 1st Armoured Division.

Various reports suggested anti-government protesters had gathered around the barracks. At some point shots were fired, but it remains⁶ unclear who fired first.