More than 6,500 troops and police hunted for a massive Irish Republican Army weapons cache believed smuggled into the Irish Republic in four boatloads from the Mediterranean region in the last two years. Irish Justice Minister Gerry Collins said three shipments were loaded off the islands of Malta and Gozo and one was loaded off the shores of Libya. However, he said there was no proof that Libya was the supplier. In Northern Ireland, security forces joined in the search, triggered by the seizure of 150 to 200 tons of arms from a ship by French customs officials Oct. 30. These arms were destined for the IRA, authorities said, and interrogation of suspects indicated that the earlier shipments had already reached Ireland.