Rebels in Syria on Thursday bombarded the Menagh air base that was being used by helicopter gunships and other warplanes to attack the northern city of Aleppo, sources said.

"Menagh military airport was bombarded on Thursday morning by a tank captured previously by the rebels," the Syrian Observatory for Human Rights said of the base 30 kilometres (18 miles) northwest of the country's commercial capital.

An AFP reporter who heard and saw the bombardment said rebels told him it was "an attack to take this airport being used by helicopters and planes that are firing on Aleppo.

The United Nations confirmed on Wednesday that rebels battling President Bashar al-Assad's regime now had heavy armour, and that its military observers had seen the Syrian military use a fighter jet to attack the rebels in Aleppo.

"The observers now have confirmed information that the opposition is in possession of heavy weapons including tanks in Aleppo," UN spokesman Martin Nesirky told reporters at UN headquarters.

AFP correspondents on the ground have reported that rebels have captured a number of tanks, and some armoured units have defected with their vehicles.

Panetta in Jordan for talks on Syria
Amman (AFP) Aug 2, 2012 - US Secretary of Defence Leon Panetta arrived in Jordan on Thursday for talks with King Abdullah II on the conflict in neighbouring Syria and the influx of refugees to Jordan.

"Both of our nations share concerns about what is happening in Syria and the impact that that could have on regional stability," Panetta told reporters before arriving in Amman on a last leg of a regional tour of Tunisia, Egypt and Israel.

"We are working very closely with them (Jordanians) along with a lot of international and non-governmental partners, to provide humanitarian assistance to support those that have been affected by violence in Syria."

Jordan, which is currently hosting more than 145,000 Syrians, on Sunday opened a refugee camp with the aim of helping those have fled escalating violence across its northern border.

The Zaatari camp in Mafraq can take up to 120,000 people.

More than 276,000 Syrians have fled their country mainly to Jordan, Turkey and Lebanon, according to the UN refugee agency UNHCR.

"The department of defence has reached unprecedented levels of cooperation with the Jordanian armed forces. We have done that in light of what is happening in Syria," Panetta said.

"We have done that in a way to try to develop as close a partnership as possible to deal with any contingency that may happen there."

The king on Wednesday visited the border village of Tal Shehab, where he and Jordanian troops had iftar meal to break the Ramadan fast, the palace said.

"At dawn, 600 Syrians came under Syrian army fire as they fled to Jordan. The Jordanian army responded and allowed them to cross," said Zayed Hammad, head of the Ketab and Sunna Society which cares for thousands of Syrians who have fled the violence.

"Nobody was hurt. This happens all the time, but this morning's fire exchange took longer than usual."

Syrian troops opened fire last Thursday on a group of civilians fleeing into Jordan, killing a three-year-old child.

The conflict in Syria has killed more than 20,000 people since the uprising against the regime of President Bashar al-Assad erupted in March 2011, the Syrian Observatory for Human Rights says.