A cease-fire between Israeli forces and an alliance of Palestinian guerrillas and Lebanese leftist militiamen generally held into its eighth day today, although some artillery and machine gun fire was reported in West Beirut's southern suburbs, the site of Palestinian refugee camps.

At one point, Israeli artillery and guerrilla gunners dueled for an hour near the shut-down international airport on Beirut's southern outskirts.

Israeli aircraft made several passes high over the city at midday, apparently on reconnaissance missions.

Elsewhere in Lebanon, Syria and the Palestinians have been reinforcing their units in eastern Lebanon's Bekaa Valley, and the Israelis have been matching the effort in adjacent zones under their control, diplomatic sources reported. The extent of the buildups was not clear.

In Damascus, Syrian President Hafez Assad was quoted as saying that Syrian troops will remain in Lebanon as long as Israeli forces are on Lebanese soil. He told a gathering of Moslem leaders that Syria still has troops in Beirut, but did not say how many. Military observers have calculated that less than half a brigade of Syrian troops remains in West Beirut. Syrian forces have been deployed in Lebanon since the 1975-76 civil war as peace-keeping troops.