The Syrian army has said that Israeli jets crossed into Syria below the radar level at dawn and hit a military research Centre in Jamraya, near Damascus.

"Israeli fighter jets violated our airspace at dawn today and carried out a direct strike on a scientific research Centre in charge of raising our level of resistance and self-defense," the army's general command said in a statement carried by state news agency SANA on Wednesday evening.

The strike came "after terrorist groups made several failed attempts in the past months to take control of the site," the statement added of opposition groups fighting the regime of President Bashar al-Assad.

Israeli warplanes entered Syrian airspace via Mount Hermon, or Jabal el-Sheikh in Arabic, the army said.

"They... carried out an act of aggression, bombarding the site, causing large-scale material damage and destroying the building," state television quoted the military as saying.

The army added that two site workers were killed in the strike.

Hezbollah fears

The army denied earlier reports that Israeli forces had launched an air strike overnight on a weapons convoy from Syria near the border with Lebanon.

Media reports quoted US and regional officials as saying that Israel had conducted an airstrike inside Syria near the border with Lebanon, hitting a convoy of trucks.

"The target was a truck loaded with weapons, heading from Syria to Lebanon," said one Western diplomat on Wednesday. 

A source among opposition forces fighting Assad said an air strike around dawn (04:30 GMT) on Wednesday blasted a convoy on a mountain track about five kilometers south of where the main Damascus-Beirut highway crosses the border.

The regional officials said Israel had been planning in the days leading up to the airstrike to hit a shipment of weapons bound for Hezbollah in Lebanon.

They said the shipment included sophisticated, Russian-made SA-17 anti-aircraft missiles, which would be strategically "game-changing" in the hands of Hezbollah.

A US official confirmed the overnight strike hitting a convoy of trucks.

All the officials spoke on condition of anonymity because they were not authorized to discuss the strike.

'No comment'

Israel and the United States declined to comment.

"I don't have any comment for you on those reports," said White House spokesperson Jay Carney, when asked about the  strike.

"I'd refer you to the government of Israel for questions about deliberations or actions that they may or may not have taken," he said.

Among Israeli security officials' chief fears is that Hezbollah could get its hands on Syrian chemical arms and SA-17 anti-aircraft missiles.

If that were to happen, it would change the balance of power in the region and greatly hinder Israel's ability to conduct air violations in Lebanon.

Airspace violation

The military in Lebanon, which shares borders with both Israel and Syria, said on Wednesday that Israeli warplanes have sharply increased their activity over Lebanon in the past week, including at least 12 sorties in less than 24 hours in the country's south.

A senior Lebanese security official said there were no Israeli airstrikes inside Lebanese territory. Asked whether it could have been along the border on the Syrian side, he said that that could not be confirmed as it was out of his area of operations.

He spoke on condition of anonymity because he was not authorized to speak to the media.

A Lebanese army statement said the last of the airspace violations took place at 2am local time on Wednesday. It said four warplanes which flew in over the southernmost coastal town of Naqoura hovered for several hours over villages in southern Lebanon before leaving Lebanese airspace.

It said similar flights by eight other warplanes were conducted on Tuesday.

Israeli violations of Lebanese airspace occur on a daily basis and Lebanese authorities routinely lodge complaints at the UN against the flights.

PHOTO CAPTION

This graphic shows the location of a Wednesday, Jan. 30, 2013 Israeli airstrike on a military target in Jamraya, Syria, about 15 kilometers (10 miles) from the border with Lebanon.

Aljazeera