Gunfire and shelling rocked Sanaa for the third straight day yesterday, killing seven people, as the casualty toll from the worst outbreak of violence in months spiralled to 60 dead and hundreds wounded.

Vice President Abdrabuh Mansur Hadi called for a ceasefire, while EU foreign policy chief Catherine Ashton urged an end to the violence and pressed embattled President Ali Abdullah Saleh to accept a transfer of power.

And the international Red Cross said some Red Crescent teams had been threatened and assaulted in Yemen and that violent confrontations were reportedly taking place in one of Sanaa’s main hospitals.

Fighting between dissident troops and those loyal to President Saleh broke out at dawn after a brief lull overnight and raged through the day, leaving seven people dead, before receding in the evening, medics and witnesses said.

“Four civilians and three soldiers from the First Armoured Brigade were killed,” a medical official said, referring to the dissident troops loyal to General Ali Mohsen al-Ahmar.

Republican Guard troops, commanded by Mr Saleh’s son, Ahmed, shelled posts held by General Ahmar’s troops around Change Square, epicentre of the anti-regime protests that have shaken Yemen for months, witnesses said.

Change Square was targeted by mortar rounds and anti-aircraft fire, with one witness describing it as the “heaviest shelling” yet and saying it “lit the sky over the square”.

A shell also hit Al-Iman University near the square killing one and wounding three, said university spokesman Ayed al-Zindani.

Mortar rounds struck near the field hospital set up at Change Square and six people were wounded, said activist Walid al-Amari.

Snipers and security forces also opened fire on demonstrators who tried to march towards the Kentaky crossroad, where the office of Ahmed Saleh is located.

Medics at the Change Square field hospital reported dozens were wounded in the shooting.

Protest organisers said the numbers of demonstrators camped in an area stretching about three kilometres from Change Square to Al-Zubair Road had swelled to nearly 150,000.

Referring to Vice President Hadi, a defence ministry source said he had given “strict orders for a rapid ceasefire in the capital and that government forces were obeying”.