|Soldiers loyal to Saleh attacked 'Change Square' in Sanaa on Saturday [Reuters]
Forces loyal to President Ali Abdullah Saleh have intensified their assault on opposition protesters, attacking unarmed demonstrators in Sanaa's "Change Square" and the headquarters of defected soldiers - leaving scores dead and injured just one day after the president returned from a three-month absence in Saudi Arabia.
The main opposition protest camp in Sanaa came under heavy mortar fire and sniper attack by Yemeni government forces on Friday. Reports indicate that at least 16 people were killed and 54 injured in the assault.
Troops loyal to Saleh launched the attack a little after midnight on Friday, opening fire with guns and shelling "Change Square", which protesters first occupied back in January.
Muttahar al-Masri, Yemen's interior minister, however denied that a raid took place, blaming the gunfire on "extremists".
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Snipers also targeted the people in the square from buildings around it, witnesses said.
Medics working at a field hospital set up in the square said that some of those killed were mangled.
"We have ... one killed in a terrible way by the mortar fire - we only have half a body," Dr Mohammed al-Qubati said.
Hundreds fled from the southern end of the camp, witnesses said, as the attack continued through Saturday morning.
Elsewhere in Sanaa, pro-Saleh shelled the headquarters of the First Armoured Division - the unit of defected soldiers supporting the Yemeni people's revolution.
Reports said 11 soldiers were killed and 120 injured in the shelling.
The fatalities brought the number of those killed to at least 47 since Friday - and to 142 since Sunday, when the ongoing wave of violence hit the Yemeni capital.
The main military rival of Saleh said the returning leader was set on driving the country into civil war and called on the international community to rein him in.
Major General Ali Mohsen al-Ahmar issued a strongly worded statement on Saturday, calling Saleh a "sick, vengeful soul'' and comparing him to the Roman emperor Nero, burning down his own city.
Many Yemenis thought they had seen the last of Saleh when he flew to Saudi Arabia in June for medical treatment after a bomb explosion at his palace left him with severe burns.
His reappearance raised big questions over the future of the fractious Arabian Peninsula state.
In Washington, White House spokesman Jay Carney said: "We urge President Saleh to initiate a full transfer of power and arrange for presidential elections to be held before the end of then year.
"The Yemeni people have suffered enough and deserve a path towards a better future."
Yemen's Saleh calls for ceasefire on return from Riyadh
A senior Saudi official told AFP news agency that Saleh had returned from Riyadh to put his house "in order" and "prepare for elections".
Saleh will "leave" after this, the official said 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.
Saleh had been involved in the negotiations, repeatedly promising to step down only to change his position at the last minute.
"I return to the nation carrying the dove of peace and the olive branch," Saleh was quoted as saying by state television on Friday.
He also called for a ceasefire.
However, the violent crackdown on anti-Saleh protesters by pro-Saleh forces have left many Yemenis skeptical of his intentions.