Of the dead in Sanaa, two were loyal to Gen. Ali Muhsen Al-Ahmar, who has defected to the opposition, a government security official said. The other three were regime soldiers.

Government forces were sending in armored vehicles as reinforcements to the demonstrations in Sanaa, the official said.

Thousands of Yemenis took to the streets in Aden, Taiz, Hodeida and Dhamar.

In addition to the dead in Sanaa, two people were killed in Aden, according to medical staff at the city's Naqeeb Hospital.

Meanwhile, Yemen's attorney general threatened to resign unless the government went after the killers of anti-government protesters last month.

Abdullah Al-Olufi said "those who were responsible for killing almost 60 protesters and injuring hundreds of others should be identified and brought to justice soon."

Protests erupted in Yemen this week despite an attempt by Persian Gulf nations to decrease tensions.

The Gulf Cooperation Council has urged Saleh to transfer powers to his vice president, a move that falls short with the protesters who returned to the streets for marches. Opposition leaders vowed not to back down.

Saleh, in power since 1978, said he welcomes the council's efforts to help resolve the political crisis in his country. He has said he intends to step down but only under a peaceful and constitutional transition process. He has already promised not to run in the next round of elections.