After more than a decade of secrecy, Israel has confirmed it has conducted a 2007 military raid on what was believed to be a Syrian nuclear reactor.

The Israeli army said a total of eight F-16 and F-15 fighter jets bombed a Syrian nuclear facility in Deir Az Zor, 450km north of Damascus, in a stealth operation that lasted four hours overnight on September 5 to 6, 2007.

The attack, dubbed "Out of the Box" by Israel's military command, was long known to have occurred but was kept under an 11-year gag order forbidding Israeli media to publish details on the operation.

"The message from the attack on the nuclear reactor in 2007 is that the State of Israel will not allow the establishment of capabilities that threaten Israel's existence," said Israeli army chief of staff Gadi Eizenkot.