The Israeli navy captured a group of Palestinian guerrillas in boats off the southern coast of Lebanon, Israeli state radio reported. The radio, quoting a military spokesman, said the guerrillas belonged to Fatah, the mainstream faction of Palestine Liberation Organization Chairman Yasser Arafat. The boats were headed southward from the Lebanese port of Sidon, the spokesman said. He refused to comment on the fate of anyone aboard the boats. The seizure occurred Sunday, and there was no explanation as to why the Israel Defense Forces waited three days to announce it.