Black smoke billows from an area in Sanaa after government troops fought with rival forces on Saturday [AFP]

Dawn gunfire in the Yemeni capital, Sanaa, has killed one person and wounded six others, with anti-government protesters accusing snipers of targeting their protest camp.

The day after streetfighting between troops loyal to President Ali Abdullah Saleh and soldiers and armed tribesmen who defected to the opposition, tens of thousands of demonstrators set off on a protest march on Sunday from Change Square.

Change Square is the street intersection next to Sanaa University on the capital's ring-road where the opposition has set up camp.

"There are one dead and six injured due to firing in the south of Change Square at dawn," Dr Mohammed al-Qubati, the head of a field hospital set up in the protest camp, said.

Protesters said it had been government snipers shooting at them.

Medics and government officials said the total death toll from Saturday's fighting had risen to 20, including four civilians and five soldiers. Dozens of others were wounded.

A nine-month confrontation between Saleh and a fractured opposition of student protesters, tribal leaders and dissident army factions escalated in recent weeks after a three-month lull.

The heightened fighting comes after Tawwakul Karman, a protest leader, won the Nobel Peace Prize earlier this month, and a United Nations Security Council resolution, passed on Friday, calling on Saleh to immediately sign a deal under which he would quit.

Karman criticised the resolution for not opposing a proposal by the Gulf C-ooperation Council (GCC) that would give Saleh immunity from prosecution if he signs the deal.

Saleh has backed away three times from a transition plan brokered by the GCC and says he will only hand over power to "safe hands".

Rocket-propelled grenades, mortars and automatic weapons were used on Saturday in the al-Hasaba, Soufan and al-Nahda districts of northern Sanaa, where soldiers loyal to the opposition are based.

Hasaba is home to Sheikh Sadeq al-Ahmar, a prominent tribal chief who opposes Saleh.