The UN humanitarian chief briefly visited the battered Homs neighbourhood of Baba Amr with a Syrian Red Crescent team on Wednesday, as Washington revealed it is mulling non-lethal aid to the rebels.
Valerie Amos was stopped from going into areas of Homs still held by the opposition, despite receiving assurances from Syrian Foreign Minister Walid al-Muallem in earlier talks that she could go to any part of the country, her spokeswoman Amanda Pitt told AFP.
"She says that the parts they saw were completely devastated," Pitt told AFP. "She said Homs feels like a city that has been completely closed down.
"There were very few people around. They did see a few people looking for their belongings, that kind of thing."
The group "tried to get into opposition areas, but they were not able to do so. Security was definitely an issue. They heard gunfire as well," Pitt said.
The Syrian Observatory for Human Rights said a child was among four people shot dead on Wednesday in Khaldiyeh, a Homs neighbourhood where rebels remain active.
They were among 19 people killed in violence nationwide, the Britain-based watchdog added.
The Red Crescent and the International Committee of the Red Cross had been trying since last Friday to enter Baba Amr -- the target of a month-long bombardment to oust rebel fighters -- but the government repeatedly barred them from evacuating wounded civilians and delivering desperately needed supplies.
Amos and the Red Crescent team were only able to make a lightning tour of Baba Amr during her hard-won visit, ICRC officials said.
"Amos entered with the team of volunteers from the Syrian Red Crescent, which stayed 45 minutes in the district," ICRC spokesman Hisham Hassan said in Geneva.
Aid was being distributed to the displaced civilians in the areas where they had found refuge and some 350 families had been given assistance over the past two days, he said.
Last week, ICRC president Jakob Kellenberger called the government's decision to deny aid workers access to Baba Amr "unacceptable."
The authorities said the earlier ban was prompted by safety concerns but the opposition charged that the delay was aimed at allowing time for the regime's "crimes" to be covered up.
Amos flew in to Damascus for a two-day visit after an international outcry over the earlier refusal of President Bashar al-Assad's regime to let her in.
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She is to be followed by UN-Arab League envoy Kofi Annan on Saturday.
The former UN chief was in Cairo on Wednesday ahead of his first visit since his appointment as international envoy for Syria.
In his talks with Amos, Muallem "underlined Syria's commitment to cooperate with the delegation within the framework of the respect, sovereignty and independence of Syria," state SANA news agency said.
Observatory chief Rami Abdel Rahman said the overall death toll since last March has now reached almost 8,500, with civilians accounting for three-quarters of those killed.
Meanwhile, US Defence Secretary Leon Panetta said Washington was looking at delivering non-lethal aid to rebel forces, while warning of the risks of military action against Assad's regime without international consensus or a unified opposition.
While outraged at the killing of civilians in Syria, the US government is opposed to taking unilateral military action and favors pursuing diplomacy to force Assad to step down, Panetta told the Senate Armed Services Committee.
Asked by Senator Richard Blumenthal if the United States was ready to deliver communications equipment to Syrian rebels, Panetta said: "I'd prefer to discuss that in a closed session but I can tell you that we're considering an array of non-lethal assistance."
His answer marked the first time President Barack Obama's administration had suggested it was ready to provide direct assistance to Syria's rebels, who are badly outgunned by the regime's tanks and artillery.
The Pentagon chief condemned the Syrian regime's crackdown but expressed caution about military intervention, citing a lack of international consensus, a deeply divided resistance and the risk of fueling a civil war.
"We are reviewing all possible additional steps that can be taken with our international partners to support efforts to protect the Syrian people, end the violence and ensure regional stability, including potential military options if necessary," Panetta said.
"Although we will not rule out any future course of action, currently the administration is focusing on diplomatic and political approaches rather than a military intervention," he said.
Tunisian President Moncef Marzouki renewed an offer of asylum to Assad in an interview to be shown Thursday, after Russia said the Syrian leader said there was no question of it granting the Syrian leader refuge.
Incoming president Vladimir Putin had rejected the idea of Russia offering Assad refuge as a way of helping put an end to nearly a year of bloodshed in its Soviet-era ally.
"We are not even discussing this question," news agencies quoted him as saying.