Syria yesterday said it had opened fire on Israeli aircraft after they crossed into Syrian airspace, broke the sound barrier and "dropped ammunition" over the desert.
The claim comes after several months of shifting and sometimes tense relations between Israel and Syria.
A Syrian military spokesman was quoted on the state news agency as saying that shortly after midnight the Israeli aircraft had crossed into north-east Syria from the Mediterranean, close to the Turkish border. Reports said the incident happened near al-Abyad, close to the border.
"Air defence units confronted them and forced them to leave after they dropped some ammunition in deserted areas without causing any human or material damage," the spokesman said. "We warn the Israeli enemy government against this flagrant aggressive act, and retain the right to respond in an appropriate way."
It was not clear exactly what the aircraft had dropped and the Syrian news agency did not say any targets had been hit.
"We are a sovereign country. They cannot do that," said Buthaina Shaaban, a Syrian cabinet minister.
The Israeli military said it had no comment on the incident. "We cannot discuss military operations," a spokesman said. In Washington, a White House spokesman also declined to comment.
Israeli aircraft frequently fly over Lebanon, sometimes breaking the sound barrier, and operate on training missions in Turkey. But flights over Syria are less commonly acknowledged, although Israeli aircraft flew into Syrian airspace last summer, after the capture of an Israeli soldier near Gaza, and again at the start of the war with Hizbullah in Lebanon.
Israel's military does monitor activities near the Golan Heights, but yesterday's incident occurred a considerable distance away.
Israel's border with Syria has been its quietest in the past 30 years and it emerged earlier this year that secret peace talks had been held between some Israelis and the Syrian government over the previous two years to draw up a formal peace treaty, although they eventually broke up without success.
Since then the Israeli press has repeatedly forecast a brewing conflict with Syria, although that prompted both Israeli and Syrian officials to say publicly they do not intend to go to war. Israel said it had begun to reduce troop levels near the Golan Heights, captured from Syria during the 1967 war and later annexed to Israel.
Syria has fired on Israeli fighter jets after they claim that the planes entered Syrian territory "dropping ammunition" and traveling at the speed of sound.

"Air defense units confronted them and forced them to leave after they dropped some ammunition in deserted areas without causing any human or material damage. We warn the Israeli enemy government against this flagrant aggressive act, and retain the right to respond in an appropriate way," said a spokesman for the Syrian military force.

Israel has neither confirmed or denied the reports, simply stating that "we cannot discuss military operations." Past Israeli military operations into Syrian airspace have been confirmed by the Israeli military, such as the circling of Syrian President Bashar Assad's compound in 2006. 

Israel, in the past, would fly over Lebanon and Turkey to perform training exercises and have at times traveled at the speed of sound. The last reported Israeli fighter planes to fly into Syria was in 2006 after an Israeli soldier had been kidnapped. They also flew into Syria just before the armed conflict with Hezbollah in Lebanon had begun.

Syria has said that no targets were hit and that no one was injured in the incident.