"Today, Yemen is newborn," sang dozens of youths in Sanaa's University Square -- dubbed "Change Square" -- the epicentre of anti-regime protests that have raged against Saleh's rule since January.

"This is it, the regime has fallen," others chanted.

In Yemen's second-largest city Taez, a flashpoint of anti-regime demonstrations south of Sanaa, hundreds also celebrated, chanting: "Freedom freedom, Ali has fled."

Saleh, 69, wounded by a blast as he prayed at a mosque inside his presidential compound on Friday, was transferred to Riyadh for medical treatment late on Saturday, a Saudi official said.

The president, in power since 1978, has not stood down and will return to Yemen, the official said.

The embattled leader flew to Riyadh on a Saudi medical aircraft and was immediately taken to the capital's military hospital, while a second plane carried members of his family, he said.

His eldest son Ahmad, commander of the elite Republican Guard, remained in Yemen. The opposition says Ahmad was preparing to take over from his father before the popular uprising started.

The blast at the presidential palace's mosque killed 11 people and wounded 124 others, according to an official toll.

The embattled leader suffered "burns and scratches to the face and chest," an official said, after the ruling General People's Congress party had said he was only "lightly wounded in the back of the head."

In Sanaa, a presidential palace source confirmed the departure of Saleh, who under the constitution is to be replaced by Vice President Abdrabuh Mansur Hadi in his absence.

State television, meanwhile, broadcast songs in praise of Saleh.

Sanaa, where battles since last month between Saleh's troops and opposition tribesmen loyal to powerful chieftain Sheikh Sadiq al-Ahmar have killed dozens of people, was calm on Sunday after sporadic overnight gunfire.

A source close to Sheikh Sadiq said the powerful tribal chief was "committed to a ceasefire based on mediation efforts led by Saudi King Abdullah and Crown Prince Sultan bin Abdul Aziz despite continuous shelling" by Saleh's forces.

Meanwhile, a committee of organisers of anti-regime protests called on citizens to set up committees to protect public properties from looters, in a statement late on Saturday.

The appeal came after residents in Taez reported looting and said armed men had seized public buildings following a pullout by security forces who killed at least 50 people in a crackdown on anti-Saleh protesters last week.