BELGRADE, Yugoslavia -- Two Croatian policemen were killed in clashes with Serbian guerrillas Friday and an European Community helicopter carrying cease-fire observers was forced down by gunfire, officials said.
The policemen were killed in fighting with guerrillas in the town of Okucani, about 100 miles southeast of the Croatian capital of Zagreb, Croatian sources said.
Serbian guerrillas, operating out of Serbian enclaves in Croatia, in the past month have seized about one-third of Croatia's territory from Croatian forces. Rebel Serbs claim their 'liberated' enclaves will never again be part of Croatia, whether the republic remains part of the six-republic Yugoslav federation or secedes from it.
A declaration of independence by Croatia has not been recognized by the Yugoslav federal government.
Gunfire from the ground pierced the windshield of a helicopter carrying two Dutch pilots and two observers from Luxembourg and Italy, an EC spokesman said. The helicopter made an emergency landing at a farm in Novska, 60 miles east of Zagreb, but no one aboard was injured.
The white helicopter, which was clearly marked as belonging to the EC, was flown back to Zagreb, the spokesman said.
The EC observers were in Croatia to monitor a cease-fire that took effect Aug. 7.
Meanwhile, another round of prisoner exchanges was held overnight in eastern Croatia, bringing to nearly 200 the number of Serbians and Croatians exchanged in three months of fighting in the breakaway republic.
Croatian officials said progress was made on working out details of a Croatian-Serbian observer group to monitor, with the Yugoslav army, the cease-fire.
Sporadic shooting was reported overnight in and around Osijek, a Serbian stronghold and the biggest town in eastern Croatia. No serious injuries or heavy damage was reported, the Yugoslav news agency Tanjug said.
Strong explosions were also reported in the area of Beli Manastir east of Osijek, but their cause was not immediately known.
Osijek Mayor Zlatko Kramaric said 43 persons were released from the Osijek prison Thursday night in exchange for 32 persons detained in Borov Selo.
During a news conference in Osijek Friday, Croatian government member Drazen Budisa said the idea of the observer commissions was high on the agenda during talks Thursday with members of working groups from the federal cease-fire commission, Croatian government, and representatives of Osijek and the Serbian people in the Slavonija area.
In an unrelated incident, two persons were killed when a bomb-laden car exploded in Herceg-Novi on the southern Adriatic coast in the republic of Montenegro, police said.
The Soviet Lada car carried plates issued in the republic of Bosnia- Herzegovina. Authorities found pieces of an explosive device with a timer in the car and two more similar devices packed in a fruit juice container.
Police believe the bombs were the work of a terrorist group from the extremist wing of the Democratic Action Party of Bosnia-Herzegovina.