DAMASCUS – Syrian air defenses opened fire on Israeli aircraft after they violated Syrian airspace, Syrian officials said today, sharply elevating cross-border tensions.

The Israelis flew east from the Mediterranean Sea over the northern part of the country, broke the sound barrier and “dropped ammunition” over deserted areas of Syria overnight, the spokesman was quoted as saying by the official Syrian Arab News Agency.

“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,” 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 if Syria was accusing the Israelis of using warplanes or some type of other aircraft such as drones. The Syrians did not say the aircraft struck targets, and it was not clear what the spokesman meant by dropping ammunition. Warplanes sometimes drop extra fuel tanks to make the aircraft lighter and easier to maneuver.

An Israeli army spokesman declined to comment, saying he could not discuss military operations.

Asked if Israel had attacked his country, a Syrian cabinet minister, Buthaina Shaaban, said on Al-Jazeera television’s English service that the aircraft violated Syrian airspace.

“We are a sovereign country. They cannot do that,” Mr. Shaaban said.

Syria’s information minister, Mohsen Bilal, said the government was “seriously studying the nature of the response,” but did not say in an interview with Al-Jazeera whether the reaction would be on the military or diplomatic level.

It is unclear if, or how often, Israeli aircraft fly over Syria.

Israel acknowledges flying over Lebanon routinely and is believed to fly routine reconnaissance flights over the Golan Heights to monitor Syrian army moves near the disputed territory. Witnesses said today’s incident occurred over the other side of Syria, in the al-Abyad area near the northeast border with Turkey near the Mediterranean.

Syrian officials, including President Bashar Assad, have repeatedly warned Israel in recent weeks that the occupation of the Golan Heights “cannot last forever.”

Partly as a result of those statements, concerns grew over the summer that tensions along the frontier could escalate into conflict. But both Syrian and Israeli officials publicly and repeatedly said they had no interest in war.

Late last month, Israeli security officials said the army had determined that war with Syria, whose military had reduced its war readiness, was unlikely and Israel began rotating forces out of the Israeli-held Golan Heights.

An Israeli counterterrorism expert, Boaz Ganor, said that if today’s overflight occurred, it’s possible Israel was “collecting intelligence on long-range missiles” deployed in northern Syria.

A Syrian political analyst, Imad Fawzi Shoaibi, said that Israel may have been probing new air defense systems provided by Russia.

The Syrian military spokesman did not specify whether the military used surface-to-air missiles or anti-aircraft artillery against the aircraft.

Syria is believed to be unhappy that other Arab countries are headed to a peace meeting in November at which America hopes for a high-profile meeting between the Palestinian Arabs and Israelis, and perhaps also with Saudi officials.

Syria has long disputed any notion that a comprehensive Arab peace deal can be reached unless it also involves some resolution of the Golan Heights, which it wants back in full.

At the beginning of last summer’s war against Hezbollah guerrillas in Lebanon, Israeli warplanes buzzed the palace of President Assad of Syria in what analysts called a warning to Damascus. They also flew over Mr. Assad’s summer home in the coastal city of Latakia, after Syrian-backed Palestinian Arab militants in Gaza captured a young Israeli soldier.

In October 2003, Israeli warplanes bombed a Palestinian Arab guerrilla base near Damascus, the first airstrike since the 1973 war.