Activists said 77 killed on Friday UN-Arab League envoy Kofi Annan has arrived in Syria for talks with President Bashar al-Assad, in a fresh diplomatic bid to end the violence. UN chief Ban Ki-moon said Mr Annan would call for an immediate ceasefire by the army and the opposition.
Meanwhile, Saudi foreign minister Saud al-Faisal on Saturday told his Arab and Russian counterparts that a Russian-Chinese veto of a UN resolution condemning Syria allowed the regime's "brutality" to continue.
The stand of "the countries that thwarted the UN Security Council resolution and voted against the resolution of the General Assembly on Syria gave the Syrian regime a licence to extend its brutal practices against the Syrian people, without compassion or mercy," he said.
Mr Annan arrived at Damascus airport on Saturday and was met by Syrian Deputy Foreign Minister Faisal Mekdad, before being taken to a hotel in the capital ahead of the talks with the president.
Mr Annan's meeting with President Assad was earlier announced in New York by Mr Ban, the UN secretary-general.
Mr Ban said he had held a conference call with Mr Annan and Arab League secretary-general Nabil al-Arabi.
"All three of us share the same concerns, same priorities and same approaches," he said.
"Our priority is, first of all, all violence must stop, whether by government forces [or] opposition forces.
"I have very strongly urged Kofi Annan to ensure that there must be an immediate ceasefire."
He said that if a ceasefire could not be agreed simultaneously, then government troops should stop first, followed by the opposition.
Mr Ban said Mr Annan - a former UN secretary-general - would also meet foreign minister Walid al-Moallem in Damascus and then hold talks with opposition leaders after leaving the country on Sunday.
The UN has called for "dialogue" to end the crisis, although opposition groups have already rejected the idea of talks with President Assad.
Mr Ban also echoed Baroness Amos's calls for Syria to allow aid agencies access to areas badly hit by the violence.
He said that what she had seen in the devastated Baba Amr district of Homs showed there was a "quite serious, alarming situation in terms of humanitarian assistance and human rights".
On Friday, Baroness Amos said the government had indicated that an initial humanitarian assessment could be made within the next week, and that a UN team in Damascus was ready to get to work.
"They have agreed to a limited preliminary assessment to try to find out where people are and what they need, but I would like something much more comprehensive," she told the BBC.
Baroness Amos also toured camps on the Turkish-Syrian border where about 11,000 Syrians have taken refuge.
Meanwhile, Burhan Ghalioun, the leader of the main opposition group, the Syrian National Council, said any talks with Assad were pointless as long as the regime continued to massacre its own people.
"It feels like we are watching the same movie being repeated over and over again," Ghalioun told the Associated Press in an interview from Paris. "My fear is that, like other international envoys before him, the aim is to waste a month or two of pointless mediation efforts."
For its part, China announced on Friday that it was sending its own envoy to Saudi Arabia, Egypt and France to explain its proposal for a Syrian ceasefire. The foreign ministry spokesman Liu Weimin said the assistant foreign affairs minister, Zhang Ming, would meet Arab League leaders during the seven-day trip, which begins on Sunday.
Meanwhile, tens of thousands of people were again reported to be protesting on the streets across Syria on Friday.
Activists from the UK-based Syrian Observatory for Human Rights said there were major demonstrations in Deraa, Latakia, Homs, Hama, Deir Ezzor and Aleppo.
Another opposition group, the Local Co-ordination Committees, said 77 people had been killed across Syria on Friday, including 26 in Homs, 28 in Idlib, six in Deraa, four in Hama, nine in and around Damascus, two in Latakia and one each in Bokamal and Aleppo.
The death toll in Idlib, near the Turkish border, includes a reported massacre in the village of Ain Larouz, in which up to 20 civilians were killed when troops opened fire, the group said.
Activists and the Observatory said troops backed by tanks were massing in Idlib to target the Free Syrian Army (FSA), the country's main rebel military force.
Some activists fear Idlib could suffer the same fate as bombed-out Baba Amr.
As the government crackdown continues, several senior Syrian military officers have defected and fled to Turkey.
The Turkish government confirmed media reports that two generals, a colonel and one other officer were among 230 Syrians who crossed the border on Thursday.
Calls for reform that began with pro-democracy protests a year ago have degenerated into violence that has brought Syria to the brink of civil war.
The UN says more than 7,500 people have died as a result of the violence.