NICOSIA –– Israel forces carried out an air strike overnight on a weapons convoy from Syria near the Lebanese border, security sources told AFP on Wednesday, speaking on condition of anonymity.

The attack came after Israel expressed concerns that Damascus's stockpile of chemical weapons could fall into the hands of Lebanon's Shiite militia Hezbollah, an ally of the Syrian regime, or other militant groups.

Israeli officials said such a transfer would be a casus belli and likely spark an Israeli attack.

"The Israeli air force blew up a convoy that had just crossed the border from Syria into Lebanon," one source said, without giving a precise location.

The source said the convoy was believed to be carrying weapons but did not specify what type.

An Israeli military spokeswoman declined to comment on the report.

A second security source, speaking on condition of anonymity due to the sensitivity of the issue, also confirmed to AFP that Israeli warplanes had hit a convoy allegedly carrying weapons to Lebanon but said the incident occurred just inside Syria.

"It was an armed convoy travelling towards Lebanon but it was hit on the Syrian side of the border at around 2330 GMT," the source said.

Both sources reported a high level of "unusual" Israeli activity over Lebanese air space, which began on Tuesday evening and continued overnight.

The incident occurred just days after Israel moved two batteries of its vaunted Iron Dome missile defence system to the north and at a time of rising fears that the conflict in Syria could see weapons leaking into Lebanon.