Neither Israel, nor its ally the United States, nor Hezbollah, the pro-Iranian militia in Lebanon, have commented officially on the incidents, which were reported by various media outlets, that occurred west of Damascus on Wednesday.

Syrian state television had accused Israel of bombing a military research center at Jamraya, which lies between Damascus and the Lebanese border, and killing two workers.

"The strike caused heavy material damage and destroyed the building," state television said.

But Syrian rebel sources denied this portrayal, telling the news agency Reuters that the Jamraya center was struck by mortars fired by insurgents.

The Syrian army in turn denied reports that another Israeli air strike had targeted a weapons convoy heading from Syria to Lebanon.

Hezbollah's al-Manar television said only that Israeli warplanes had carried out "mock raids" over southern Lebanon, outside the Syrian border.

Convoy Lebanon-bound, say sources

Earlier, Middle East and Western sources had claimed that the convoy was heading from Syria to Lebanon and may have included anti-aircraft missiles or long-range rockets. One source quoted by the news agency Reuters speculated that Syria had been forwarding weapons sourced from Iran, Hezbollah's ally.

Late on Wednesday, the Israeli military declined to comment, and the location attributed to the convoy would not be verified because of reporting restrictions inside war-torn Syria.

Regional officials quoted by the news agency Associated Press said Israel had been planning to strike a shipment that included Russian-made SA-17 anti-aircraft missiles. In the hands of Hezbollah, with whom Israel last fought a war in 2006, these could endanger Israeli jets, helicopters and surveillance drones, they said.

Top Israeli officials recently expressed worries that the regime of Syrian President Bashar Assad could also pass chemical weapons to Hezbollah and other rebel groups hostile to Israel.

Chemical weapons transfer ruled out

According to Reuters, US and European security sources have said they were confident that chemical weapons were not in the convoy that was reportedly bombed.

The military in Lebanon, which also borders Israel, said on Wednesday only that Israeli warplanes had sharply increased over-flights across Lebanon in the past week.

The UN agency which monitors the Lebanon-Israeli border said on Wednesday it had no information of any airstrikes near the Syria-Lebanon border.

ipj/av (AP, Reuters, dpa)