At least six people have been killed in Yemen's capital, Sana'a, in renewed clashes between pro-government forces and opponents of President Ali Abdullah Saleh.

Witnesses say that some of the people died Thursday when snipers fired on anti-government protesters.

Violence in the capital has been escalating since late last week, when Yemen's youth-led protest movement stepped up demonstrations. More than 85 people have been killed since Sunday. The violence in Sana'a has included battles between government soldiers and troops loyal to a general who joined the opposition earlier this year.

There was a brief truce late Tuesday. But on Wednesday, activists and witnesses said government forces killed at least nine people. The troops fired on mourners at a mass funeral and attacked civilians in Change Square, an encampment where thousands have staged a months-long sit-in seeking the ouster of President Saleh.

Also Wednesday, a Gulf mediator left Yemen with no word on a power-transfer deal. Gulf Cooperation Council chief Abdul Latif al-Zayani left Sana'a after meeting with Vice President Abed Rabbo Mansour Hadi. The head of the six-nation council had traveled to Yemen Monday in an attempt to revive a long-stalled GCC plan that calls for President Saleh to hand over power to a deputy.

Mr. Saleh has agreed to the proposal three times since April. However, in each case, he has backed out before a deal could be signed.

The president remains in Saudi Arabia, where he is recovering from injuries sustained in a June attack on his presidential compound in Sana'a.