The Syrian government has bombed bridges as they were being crossed by wounded refugees fleeing from Homs to Lebanon, activists have reported.
According to the London-based Syrian Observatory for Human Rights (SOHR), the al-Qusayr bridge in Homs was bombed on Tuesday.
"[The bridge] is used by refugees and the wounded fleeing to Lebanon," said Rami Abdel Rahman of SOHR, to the AFP news agency.
The Avaaz activist network quoted an activist known a Ahmed in the town of Alqaseer as saying another bridge near to the Lebanese border had been bombed.
He said: "Snipers are shooting at anyone they see. The military is tightening its hold over the city.
"Two days ago they bombed a bridge that connects the Alqaseer areas with other western areas. The army also shelled another bridges in the village of Rabla.
"All access is blocked off and more checkpoints are being erected. Any person is arrested and movement is increasingly difficult."
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Above: the town of Homs in relation to the bridge reported bombed and the Lebanon/Syria border
He added that while the Free Syria Army is largely in control of the town many had fled in fear of a massacre similar to that reported in Homs after a withdrawal by opposition forces.
Another refugee was quoted by Al Jazeera as saying security forces had used helicopter gunships to attack families escaping into Lebanon,
"They started bombing us from the air with helicopters and started pursuing the families with the helicopters, and they struck. ... there were a lot of wounded and casualties. We reached the Lebanese border walking through the fields and we walked in the mud, under the rain.''
Reports of further violence emerged from across Syria on Monday evening and Tuesday, with Avaaz activists describing "black smoke rising up from the sequestered district of Baba Amr" which they said might be the regime burning evidence of war crimes.
The International Committee of the Red Cross was still unable to distribute aid in the district where hundreds of civilians were reported to have been killed in almost four weeks of continuous shelling which ended in a group assault by security forces last week.
Meanwhile Turkish prime minister Recep Tayyip Erdogan said that Syria must open access to humanitarian aid.
"Humanitarian aid corridors must immediately be opened," he told a parliamentary meeting on Tuesday.
US Senator John McCain yesterday called for air strikes against the regime to force a halt to the violence.
The United Nations believes more tan 8,000 people have been killed in Syria since the start of anti-government protests in March 2011.
Activists put the total closer to 10,000 deaths, 600 of which are believed to be children.