Thousands of armed tribesmen are reportedly heading towards the Yemeni capital of Sanaa today to support their leader Sheikh Sadiq al-Ahmar, whose fighters have been battling government security forces in the city for days.
At least 15 people were reported killed in clashes between Ahmar's supporters and security forces in Sanaa overnight.
Clashes are also being reported on June 2 in the city of Taiz between security forces and armed antigovernment protesters.
More than 40 people reportedly have been killed in Taiz this week after a truce collapsed between security forces and protesters.
The truce collapsed after President Ali Abdullah Saleh refused to sign a plan brokered by Yemen's Gulf neighbors for him to resign, as demanded by protesters since late January.
Ahmar has pledged to support the protesters.
compiled from agency reports