Troops loyal to Yemeni President Ali Abdullah Saleh killed at least five anti-government protesters early Saturday, hours after their leader called for peace following his surprise return to the country.

Saleh returned Friday after a three-month absence in Saudi Arabia recovering from injuries sustained during an attack on his palace on June 3 "carrying the dove of peace and an olive branch".

Hours later however, members of the elite Republican Guard led by his eldest son Ahmed were fighting dissident troops protecting anti-government protesters in the north of the capital Sanaa.

Saleh arrived in the city Friday during a sixth straight day of deadly clashes between troops loyal to him and heavily armed opponents.

But even as 69-year-old Saleh called for a ceasefire and talks, Washington urged the veteran president to step down.

In the latest violence, troops to loyal Saleh killed at least five anti-government protesters early Saturday in an attack on Change Square, the epicentre of anti-government protests, witnesses told AFP.

Soldiers launched the attack a little after midnight Friday, opening fire with guns and shelling the square, which protesters first occupied back in January.

Snipers also targeted the people in the square from buildings around it, witnesses said.

"At least five protesters were killed," said a medic at a field hospital set up in the square.

In the streets nearby, the president's soldiers fought with dissident troops commanded by rebel General Ali Mohsen al-Ahmar.

Witnesses said the troops attacking the square were members of the elite Republican Guard led by the eldest son of President Saleh, Ahmed.

Elsewhere in the north of the capital, fighting resumed between the president's troops and supporters of dissident tribal chief Sheikh Sadiq al-Ahmar in Al-Hasaba district, residents said.

Locals reported the sound of automatic weapons and explosions.

The latest violence brought the number of those killed to 25 since Friday -- and to 120 since a fresh wave of violence hit the capital on Sunday.

On Friday, ten of thousands of the president's supporters gathered in the capital's Sabiin Square, near his palace, to celebrate his return at the main weekly Muslim prayers.

The coffins of 24 pro-Saleh soldiers were lined up in the square, the official Saba news agency reported.

"I have returned home carrying the dove of peace and an olive branch, not holding any grudges or hatred towards anyone," the news agency quoted Saleh as saying.

He called on all Yemenis to "overcome their pain and wounds for the sake of the nation and its dignity."

But in the north of the capital, tens of thousands of Saleh opponents attended a mass funeral of 40 people killed in the most recent clashes and vowed to bring him to trial.

"The people want to bring the slaughterer to justice," they chanted.

"We thank Saudi Arabia for returning Ali to us so we can bring him to trial inside the country," said activist Mohammed al-Asal.

A spokesman for the ruling General People's Congress party, Tariq al-Shami, told AFP that "no public appearance or political activity" had been scheduled for Saleh so far.

The state news agency said the president was to make "an important speech to mark the 49th anniversary" of the September 26, 1962 revolution which saw Yemen proclaimed a republic.

Traditionally the president, who has been in power since 1978, makes his speech on the eve of the anniversary but Saba did not specify when he would deliver it this year.

But in Washington, the White House swiftly called on him to begin a "full transfer of power".

A senior Saudi official told AFP that Saleh had returned from Riyadh to put his house "in order" and "prepare for elections".

Saleh will "leave" after this, the official added, without specifying whether he would leave Yemen altogether or only leave power.

Yemen's wealthy Gulf neighbours have been trying for months to persuade Saleh to accept a plan under which he would hand over power in return for a promise of immunity from prosecution.

But the latest mediation mission to Sanaa by Gulf Cooperation Council chief Abdullatif al-Zayani foundered amid the fighting in the capital. He flew out on Wednesday empty-handed.