After months in which talk of reviving long-stalled peace negotiations has mingled with speculation on both sides that the other was preparing a surprise attack, Syrian officials hit out.

"This shows that Israel cannot give up aggression and treachery," Syrian Information Minister Mohsen Bilal told al-Jazeera television.

Another Syrian official said: "They dropped bombs on an empty area while our air defences were firing heavily at them."

The Israeli military spokesman's office said in a statement: "It is not our custom to respond to these kinds of reports."

The office has typically commented on such reports. But a security source said the government had imposed a news blackout on the issue. A spokeswoman for Prime Minister Ehud Olmert also said there would be no comment beyond the military statement.

A Israeli military source told Reuters the air force has conducted a major exercise this week. Israeli aircraft often train over Turkey, a Muslim nation friendly to the Jewish state.

An Israeli analyst familiar with defence matters said he believed Israel had been probing Syria's air defences recently.

The Syrian official news agency SANA said Israeli aircraft "infiltrated Syrian airspace through the northern border coming from the direction of the Mediterranean and headed towards northeastern territory, breaking the sound barrier".

"The Syrian Arab Republic warns the government of the Israeli enemy and reserves the right to respond according to what it sees fit," SANA added.

Local residents said they heard the sound of five planes or more above Tal al-Abiad area on Syria's border with Turkey, around 160 km (100 miles) north of the Syrian city of Rakka.

NO HOSTILE INTENTIONS

Tensions between the two neighbours have been high in recent months, with some Israeli intelligence officials suggesting President Bashar al-Assad's administration might be ready to try to take by force parts of the Golan Heights, which Israel captured in the war of 1967.

Syrian officials have said Syria is seeking peaceful means to liberate the territory, although some have also indicated that force remained an option if diplomacy failed.

Olmert, who launched his forces against Syrian-allied Hezbollah guerrillas in Lebanon a year ago, has been at pains to stress that he has no hostile intentions toward Damascus.

Some Israeli military officials have expressed alarm at what they say are reinforcements of Syrian positions and arms purchases. But Olmert has spoken out against alarmist comments.

He has also said he would like to reopen peace negotiations that have been stalled for seven years. Syrian officials, too, have said they would like peace. But there has been little sign of any concrete steps towards rapprochement.

Syria last said it fired at Israeli warplanes in June 2006, when Israeli aircraft buzzed a Syrian presidential palace.

Israeli officials said at the time the flyover was a message to cease support for Hamas after the Palestinian militant group abducted an Israeli soldier.

Israel has long warned Syria to stop supporting militant Palestinian groups and the Lebanese movement Hezbollah.

Israeli jets bombed an empty Palestinian militant training camp in Syria in October 2003.