Syria faced harsh world condemnation on Saturday as it continued to block the Red Cross from delivering desperately needed aid to the vanquished rebel stronghold of Baba Amr in the city of Homs.

Britain and Turkey joined the international outcry, accusing President Bashar al-Assad's regime of committing a crime by barring aid convoys from entering Baba Amr for the second day.

And China, which twice joined Russia in blocking UN Security Council resolutions against Syria's lethal crackdown on dissent, urged all parties in Syria to "unconditionally" end the violence.

Xinhua news agency cited a foreign ministry statement attributed to an unnamed official calling for dialogue between the Syrian regime and those expressing "political aspirations."

But the official reportedly added: "We oppose anyone to interfering in Syria's internal affairs under the pretext 'humanitarian' issues.'"

He said China was "ready to provide humanitarian assistance" and that aid should be delivered by the international community only in a way that respects "Syria's sovereignty."

As the condemnation spiralled, so did harrowing accounts of the situation inside Homs, where some 700 people were killed and thousands wounded by regime forces in a 27-day blitz, according to the US-based Human Rights Watch.

HRW said shells sometimes fell at the rate of 100 an hour and that satellite images showed 640 buildings visibly damaged, but stressed that the real picture could be worse.

British Foreign Secretary William Hague said the refusal to grant humanitarian aid access to citizens affected by the violence showed how "criminal" the regime had become.

"We will go on arguing for action at the UN and for the international community to pull together because the denial of humanitarian aid on top of all the murder, torture and repression in Syria just underlines what a criminal regime this has become," Hague said.

His Turkish counterpart Ahmet Davutoglu said the regime's "savagery must stop."

"The fact that aid is prevented and access is refused to United Nations officials constitutes another crime," Davutoglu said, calling for an international response.

On Friday a seven-truck convoy organised by the International Committee of the Red Cross (ICRC) and the Syrian Arab Red Crescent Society was barred from entering Baba Amr.

Syrian authorities said the decision was taken for security reasons, namely the presence of bombs and landmines.

But UN Secretary General Ban Ki-moon demanded unconditional humanitarian access to Syrian cities, saying there were "grisly" reports of summary executions and torture in Homs, Syria's third largest city.

"The Syrian authorities must open without any preconditions to humanitarian communities," he said. "It is totally unacceptable, intolerable. How as a human being can you bear... this situation."

By Saturday afternoon the Red Cross said that none of its teams had entered Baba Amr.

"We are still in talks," ICRC spokesman Saleh Dabbakeh told AFP.

Red Crescent operations chief Khaled Erksoussi said: "The authorities told us that we're being denied access for security reasons."

ICRC chief Jakob Kellenberger has dismissed as "unacceptable" the delay in providing emergency assistance.

Syrian troops overran Baba Amr on Thursday, capping a month of shelling which HRW, quoting accounts from journalists and residents who had fled, said would start every day at around 6:30 am and continue until sunset.

It noted that Baba Amr has been an opposition stronghold since anti-regime protests erupted last March, but stressed this presence "in no way justifies the scale and nature of the attack."

The United States has condemned the "horrific" brutality in Syria while French President Nicolas Sarkozy said what is happening "is scandalous."

The bodies veteran Sunday Times reporter Marie Colvin, an American, and French photographer Remi Ochlik were, meanwhile, finally handed over to the French and Polish embassies in Damascus.

Their remains were placed in a hospital morgue until they are flown to France.

They were killed on February 22 in a rocket attack on a Baba Amr makeshift media centre.

French reporter Edith Bouvier and British photographer Paul Conroy, who were wounded, were smuggled out of Syria and are now recovering in France and Britain respectively.

"The explosion was massive, Marie Colvin and Remi Ochlik were practically at the point of impact. They were killed on the spot," Le Figaro reported, quoting Bouvier and fellow photographer William Daniels who was with her.

Speaking of Baba Amr, Conroy told Sky News television: "It's not a war, it's a massacre, an indiscriminate massacre of men, women and children."

At least 21 more people, mostly civilians, were killed nationwide on Saturday, the Syrian Observatory for Human Rights said.

The authorities reported two dead in a suicide car bombing in the southern province of Daraa where the anti-regime uprising erupted last March, the latest in a string of such attacks since December the regime has blamed on Al-Qaeda.

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