US diplomats, family members withdrawn from Yemen

 At least 44 people have been killed since Monday in clashes between tribal fighters and government troops.

President Ali Abdullah Saleh has again said he will not step down and leave Yemen, despite mounting protests, the BBC reports.

He has so far refused to sign a transition deal that would see him resign in favour of a unity government.

The US State Department has also warned Americans against travelling to Yemen:

"The security threat level in Yemen is extremely high due to terrorist activities and civil unrest. There is ongoing civil unrest throughout the country and large-scale protests in major cities," it said.

"The Department of State has ordered all eligible family members of US government employees as well as certain non-emergency personnel to depart Yemen," the travel warning said.

"US citizens currently in Yemen should depart while commercial transportation is available."

Fighters from a powerful tribal group, the Hashid, have reportedly taken control of several public buildings in the capital Sanaa after several days of fighting government troops.

The clashes began on Monday after forces loyal to President Saleh moved against the compound of Hashid leader Sheikh Sadeq al-Ahmar.

Saleh, who has warned that Yemen can descend into civil war, refuses to stand down.

On Wednesday, US President Barack Obama said Saleh should "move immediately on his commitment to transfer power".

UN Secretary General Ban Ki-moon said he was "deeply troubled" by the violence and called on all sides to find a peaceful solution, but in a statement yesterday Saleh remained defiant, stating:

"I will not leave power and I will not leave Yemen," through spokesman Ahmed al-Soufi.

The president said he was still prepared to sign a transition deal "within a national dialogue and a clear mechanism".