In an unusual announcement, the Israeli military command said today that it has learned Syria is constructing two bases for Soviet-made SA5 ground-to-air missile batteries "deep within Syrian territory" and that Israel will continue to "follow developments concerning missile batteries."

The announcement did not claim that the missile batteries pose a threat to Israel, and civilian and military officials conceded Syria's right to install ground-to-air missiles on its own territory. The announcement appeared to have a partially political objective in reiterating that Syrian air defenses, although badly mauled by the Israeli Air Force during the war in Lebanon, are being rebuilt by the Soviet Union.

A military official said that the announcement was not intended to sound threatening and that Israel routinely makes public the installation of new weapons systems in the Arab "confrontation states" facing it.

The announcement said the bases had not yet been manned and military officials provided no information on when their construction is thought to have begun.

In Washington, State Department spokesman Alan Romberg refused to confirm the Israeli report, the Associated Press said. When questioned about it, he said, "We have been aware of the reports regarding these missiles and we would obviously regret any measure from either side in the Arab-Israeli conflict that would heighten the risks of conflicts in the region."

According to a military spokesman, the SA5 was developed by the Soviet Union during the 1960s and has not appeared outside Soviet borders before. The missile has a range of close to 200 miles, putting it within striking distance of Israeli air space, but is less modern and sophisticated than some of the Soviet-built ground-to-air missile systems that the Israelis defeated during the war in Lebanon.

During the summer and fall, Israel issued frequent warnings to Syria that it would not allow the installation of ground-to-air missiles inside Lebanon and followed these with air strikes against missile batteries the Syrians moved across the Lebanese border to protect Syrian troops in the eastern section of the country.

Today's announcement was different from those earlier threatening notices to the Syrians and appeared to have two possible political motivations.

According to Israeli sources, there is a concern here that Syria, once it is rearmed by the Soviet Union, will have less incentive to withdraw its troops from Lebanon, which Israel in turn is demanding as one condition of its own withdrawal from southern Lebanon. Israel has staked a great deal on the success of its current negotiations with the Lebanese, but whatever agreements are reached in those talks will not be implemented if there is not also agreement for a Syrian and Palestinian troop withdrawal.

Israel also is eager to remind the world, and particularly its main arms supplier, the United States, that although the Syrians were defeated in Lebanon, they have not been abandoned by the Soviet Union and are restocking sophisticated weapons with Soviet assistance. Israel emerged from the war in Lebanon more than ever as the dominant military power in the Middle East but clearly does not want to be viewed as any less threatened by Syria and other Arab states.

Appearing before the Israeli Knesset (parliament) Foreign Affairs and Defense Committee yesterday, Foreign Minister Yitzhak Shamir was quoted as saying, "We are concerned at reports that Syria recently received shipments of highly sophisticated Soviet weaponry of types never before delivered outside Soviet borders. We are troubled over reports that Soviet crews may be manning such equipment and that the Soviet government" has told Syrian President Hafez Assad "that Syrian forces in the Bekaa Valley of eastern Lebanon will be protected by the same guarantees covering Syrian forces in Syria proper."

In another development, the military command announced that last Friday Israeli forces discovered five Soviet-made Katyusha rocket launchers in southern Lebanon aimed at northern Israel's Galilee panhandle.

The independent newspaper Haaretz reported today, and Israeli sources later confirmed, that on the same day four other Katyusha launchers were discovered south of the Lebanese coastal city of Sidon.

The Katyusha rocket was a standard weapon of the Palestinian forces in southern Lebanon and ridding northern Israel of the threat of attack by them was the Israeli government's main justification for the invasion of Lebanon in June.