Up to 2,000 Syrians are crossing into northern Lebanon to flee the violence in their home country, a UN refugee agency official has said.
"Between one and two thousand (Syrians) are in the process of coming from Syria to Lebanon," Jean Paul Cavalieri told Reuters news agency.
"Numbers will become clear in the coming hours. This is what we are hearing from our teams on the ground and local authorities."
It appears they are fleeing the town of Qusair, close to the Lebanese border, which has reportedly been attacked by the regime's military.
A Reuters reporter saw women and children fleeing towards the border. They told him the military had been heavily shelling the town with tanks and they had also heard gunfire.
Meanwhile, the International Committee of the Red Cross has delivered aid to a village near Homs but aid workers are still being blocked from entering the stricken neighbourhood of Baba Amr.
It comes amid reports that Syrian government forces have raped 20 women in revenge attacks.
Emergency medical supplies, food and blankets have been distributed in the village of Abel, 3km from the city, where families who fled Baba Amr are sheltering.
Aid was also due be delivered to the nearby districts of Inshaat and Tazii by both the Red Cross and the local Syrian Red Crescent.
The Red Cross has been attempting to reach Baba Amr, where hundreds of people were killed and injured during 27 days of government shelling, since Friday.
But the Syrian authorities have continued to block access amid rising fears for the safety of the civilians still trapped.
Local activists say the government troops there are using rape "as a basic tool of fear, intimidation and repression."
Sami Ibrahim, the spokesman for the Syrian Network of Human Rights, said there were confirmed reports of at least 20 women being raped by soldiers who raided their homes.
There have also been reports of executions and mass arrests.
Activists say shelling has continued around Baba Amr.
On Saturday China called for an immediate end to the violence as international outrage over the blockage grows.
China, which twice joined Russia in blocking UN Security Council resolutions against Syria's brutal crackdown on dissent, urged all parties in Syria to "unconditionally" end the violence.
The bodies of two foreign journalists killed in shelling while trapped inside Baba Amr have been flown back to Paris from Damascus.
Red Crescent officials handed over the body of French photographer Remi Ochlik to a French Embassy official and the body of the American Sunday Times journalist Marie Colvin to a Polish Embassy official on Saturday.
Both journalists had sneaked into Syria illegally to try to get an eyewitness view of the government crackdown in the country.
They died on February 22 in shelling that also wounded Edith Bouvier of the French newspaper Le Figaro and British photographer Paul Conroy.