Syrian peacekeeping troops rounded up 50 gunmen Tuesday in pre-dawn house raids across west Beirut in what their command said was an effort to prevent the rekindling of fighting between Shiite Moslem militias.

Police said most of the arrested gunmen of the pro-Syrian Amal, Arabic for Hope, and the Iranian-backed Hezbollah, or Party of God, were released after questioning. Arms caches of undisclosed amounts also were seized.