BATTLEFIELDS were reported quiet in Croatia Wednesday after the rebel republic and the Yugoslav Army agreed on a new cease-fire that the head of a European Community mission said inspired hope of lasting peace.Early radio reports said there was a lull in the conflict, raising hopes of an end to more than three months of fighting between Croatian forces, Serbs rebelling against the republic's independence moves, and the Serb-led federal Army. In an act of defiance, the Croatian parliament ratified a declaration of independence Tuesday and severed ties with the Yugoslav federation. The neighboring republic of Slovenia quietly pushed ahead with its independence moves. But Croatian officials later agreed to the latest of several cease-fires at talks with the Army chaired by the Dutch leader of a team of EC truce monitors. "I think we have reached an agreement which has prospects for working which are better than the many cease-fire agreements we have signed before," said Dirk Jan van Houten. Agreement was reached in principle for Croatian forces to lift their blockade of federal Army barracks and for relief supplies to be sent to besieged towns across the republic. But there appeared to be no mention of a total withdrawal of federal troops from the republic, a key Croatian demand. Nor was there an immediate sign of Croatian forces lifting the blockade of federal barracks. Croatian officials say more than 1,000 people have been killed in fighting since Croatia declared independence June 25. Mr. Van Houten said the cease-fire agreement would be respected by both parties as long as they took part in an EC-sponsored peace conference on Yugoslavia's future in The Hague. The EC monitors had threatened to pull out of Croatia if no agreement was reached, an EC mission source said.