Peace Flotilla Due to Dock in Dubrovnik : Yugoslavia: Officials are trying to break the federal navy’s monthlong blockade of the Croatian port.

ZAGREB, Croatia — 

The head of Yugoslavia’s crippled federal presidency led a flotilla of 40 fishing and tour boats on a peace mission Wednesday to break the navy’s monthlong blockade of Dubrovnik, Croatia’s most cherished resort.

The boats carrying President Stipe Mesic and Croatian Prime Minister Franjo Greguric planned to reach the walled city on the Adriatic to draw attention to the plight of 50,000 people trapped inside with little food and water.

Navy gunboats halted the fleet about 50 miles north of Dubrovnik after its overnight journey from the port of Split, contending that the vessels were carrying weapons and troops.

But after hours of negotiation by telephone between Mesic and Yugoslav Deputy Defense Minister Stane Brovet in Belgrade, Croatian Radio reported that the ferry Slavija had been cleared after a search for contraband and allowed to proceed.

European Community monitors accompanying the relief fleet, however, decided to delay their entrance into Dubrovnik harbor until daylight today for fear of mines and sporadic sniper fire.

The Slavija and its trail of smaller craft carried at least 1,000 seagoing demonstrators. Except for occasional aid or evacuation boats, no other vessels have been allowed into the waters around Dubrovnik since federal warships imposed a cordon around the famous resort on Oct. 1 and Serbian-led forces began peppering it with mortars and grenades.

Croatian television showed Mesic chatting with international aid workers aboard the Slavija as it sailed toward Dubrovnik with a cargo of donated food and supplies for the city still cut off by the army from land, air and sea.

Shooting has subsided around Dubrovnik over the last few days while foreign diplomats and journalists have been escorted into the city under army protection. But fighting has continued in other areas of Croatia.

Zagreb Radio reported sporadic shelling in eastern Croatia between federal troops and republic national guardsmen holed up in the shattered city of Vukovar. The broadcast said that 1,000-pound bombs had been dropped on the city to force the estimated 15,000 holdouts from the last Croatian stronghold near the border with Serbia.

The battle for Vukovar has cost untold hundreds of lives and has come to symbolize Croatian resistance to the federal army’s incursions on behalf of Serbia. One-third of Croatian territory has been seized by army-backed Serbian rebels since June 25, when Croatia’s declaration of independence prompted the fighting.

Federal military leaders contend that their campaign is aimed at preventing genocide against the 600,000 Serbs among Croatia’s 5 million people, while Croatian officials accuse the army of trying to grab as much land as possible before agreeing to recognize Croatian sovereignty.

Croatian Foreign Minister Zvonimir Separovic told European Community leaders earlier this week that 5,000 people have been killed in the four months of war in Croatia and that nearly 400,000 have been forced from their homes to escape the fighting.

The EC has set next Tuesday as the deadline for all six Yugoslav republics to support its plan for transforming the federation into a loose alliance of sovereign states or face economic sanctions. Serbia has rejected the proposal and called for an end to EC peace talks.