Syrian tanks stormed a border town overnight, residents said on Sunday, in the latest assault to crush a three-month uprising against President Bashar al-Assad that has driven thousands of refugee to flee to Turkey.

In a pattern witnessed in other cities and towns besieged by troops and armour following street protests demanding political freedoms and end to Assad's autocratic rule, residents said loyalist forces commanded by Assad's brother Maher pushed into Jisr al-Shughour.

The strategic town, among hills on the road between Syria's second city Aleppo and the country's main port of Latakia, had seen large demonstrations, with residents describing a mutiny by security forces whom they said fought other troops to try and prevent the killing of civilians.

'Tanks came from the south after shelling randomly and sending volleys of machinegun fire all over the town. People are still fleeing from the north,' one resident said.

Bassam, a tile layer, fled to Turkey as troops were closing in on his hometown. He showed mobile phone camera footage of a dead man, between 18 and 25 years old, with a bullet wound in his leg, and a large exit wound in his stomach. He lay on a bloodied cloth.

Another picture showed a young man who had been shot in the head. He said the two were killed just outside Jisr al-Shughour by troops under the command of Maher.

'There are only a few people left. I escaped on my motorcycle through dirt tracks in the hills,' he said.

He said troops burned wheat crops in three villages near Jisr al-Shughour in a scorched-earth policy to try to crush the will of people in the strategic hill region who have been participating in large protests against Assad's rule.

Witnesses said more than 4,000 Syrians have crossed over to Turkey and up to 10,000 had taken shelter among trees near the border since forces commanded by Maher sent tanks and troops into the northwestern province of Idlib.

They said they feared revenge attacks for violence in which Syria said 120 troops were killed but which refugees and rights campaigners said resulted from soldiers mutinying following the killings of civilians.

The United States accused the Syrian government of creating a 'humanitarian crisis' and called on it to halt its offensive and allow immediate access by the International Committee for the Red Cross to help refugees, detainees and the wounded.

'When the massacre happened in Jisr al-Shughour the army split, or they started fighting each other and blamed it on us,' a woman refugee, who refused to give her name, told Turkish news channel NTV.

'Land burned'

Other refugees said the troops killed or burned cows and sheep, adding that agricultural land around the village of Sarmaniya to the south of Jisr al-Shughour had been destroyed.

The Syrian official state news agency said 'armed terrorist groups' had burned land in Idlib province as part of a sabotage scheme.

'The Syrian people are telling Bashar al-Assad we don't want you. God burns his heart. He has burned our land. He made us destitute,' the woman refugee told NTV.

Damascus has banned most foreign correspondents from the country, making it difficult to verify accounts of events. Turkey also has restricted access to refugees in camps and hospitals, saying it is to protect their privacy.

Human rights groups say security forces have killed more than 1,100 Syrian civilians in increasingly bloody efforts to suppress demonstrations calling for Assad's removal, political freedoms and an end to corruption and poverty. The protests were inspired by uprisings against other entrenched autocrats in the Arab world.

'I'm deeply concerned and saddened (that) so many people have been killed in the course of peaceful demonstrations,' UN Secretary General Ban Ki-moon told reporters during a visit to Colombia's coastal city of Cartagena.

'I've talked to President Assad several times he must take bold, immediate and decisive actions to listen to the people and to take necessary measures to reflect the will of the people.'

At the United Nations Russia and China snubbed Security Council talks on Saturday convened to discuss a draft resolution that would condemn Syria's bloody crackdown on pro-democracy protesters, UN diplomats said.

'Russia and China didn't think it necessary to show up,' a council diplomat told Reuters on condition of anonymity. 'It's a pretty clear message,' another diplomat said.

A senior Turkish diplomat said 4,300 Syrians had crossed the border and that Turkey was prepared for a further influx, though he declined to predict how many might come.

Turkey, a Sunni country that had backed Syria's ruling hierarchy, who belong to Syria's minority Alawite sect, has been increasingly critical of Assad's use of force to quell the protests as they spread to regions near the 800 km long border between the two countries.

In Washington, Jay Carney, President Barack Obama's spokesman, said: 'Syrian leaders have no excuse for denying humanitarian assistance by a neutral body like the ICRC. If Syria's leaders fail to provide this access, they will once again be showing contempt for the dignity of the Syrian people.'

Refugees could be seen walking around the grounds of a camp at Boynuyogun where tents have been pitched inside an old hangar, and another camp at Yayladagi has been established in the grounds of a disused tobacco company.

At a third site, set up in fields close to the border but so far still empty, workers carried beds into tents on Saturday.

Buffer zone

Radikal newspaper said Turkey would establish a buffer zone if migrant inflows from Syria exceed 10,000.

Just inside Syria, thousands more people were gathering close to the frontier, according to an activist helping co-ordinate the movement of refugees.

'The border area has turned practically into a buffer zone,' said the man, who identified himself only as Abu Fadi. 'Families have taken shelter under the trees and there are 7,000 to 10,000 people here now.'

Thirty-six protesters were shot dead across Syria on Friday, activists said. Syrian authorities deployed helicopter gunships in the town of Maarat al-Numaan, they added, in the first known use of air power against unrest.-Reuters