A senior official has expressed concern the Mideast fighting may provoke a full-scale confrontation between Israel and Syria, triggering greater Soviet involvement.
Like other Soviet officials, he suggested the Kremlin would prefer to avoid such an escalation, but he added: ''You know there is a treaty between the Soviet Union and Syria.'' ''Now is precisely the time a solution (to the question of the Israeli invasion of Lebanon) should be found,'' the official said.
If this is not done, he warns, at some point the Syrians will probably have to start fighting the Israelis on a large scale.
The official, a member of the Communist Party Central Committee, was interviewed June 22 as the Israelis announced fresh clashes with Syrian forces in Lebanon, including an Israeli air strike on Syrian positions near Beirut.
His remarks seemed to support the assumption of most foreign diplomats here that the Kremlin might well reassess its position of relative restraint in the Lebanese conflict should it escalate into a confrontation deemed directly to threaten Syria.
At least some diplomats fear such a reassessment could also be prompted by any full-scale Israeli move on Palestinian positions inside Beirut, but there has been no clear indication from Soviet officials interviewed that this is so.
In its public comments on the crisis so far, Moscow has avoided saber rattling. A government statement June 14 warned Israel that current Mideast developments ''cannot help but affect the interests of the USSR,'' and the Soviet news agency Tass alleged June 21 that Israeli shelling of Beirut had caused ''material damage'' to the Soviet Embassy.
But the Soviets have stopped short of pledging military backing for the Palestinians or Syrians against the Israeli invasion force. Neither of the two formal policy statements issued since the Israeli troop move has mentioned Syria.
A Tass account of talks between President Leonid Brezhnev and the visiting chief of the Portuguese Communist Party, which appeared in Pravda June 22 made only a brief reference to the Mideast crisis.
Diplomats here confirmed over the weekend that a Soviet airlift to the Syrian capital of Damascus was continuing. They stress the operation seems far more limited in scale than Soviet air activity during the 1973 Mideast war, but a military attache told the Monitor that the airlift widened somewhat by the end of last week.