Sarajevo Blast Injures 3; Serbian Rebels May Snarl Talks : Balkans: Cooperation in peace effort may be tied to lifting sanctions. Stance imperils any settlement.

An explosion in a suburban courtyard Saturday injured a man and two children in Sarajevo, and Bosnian Serb rebels insisted that U.N. sanctions be lifted before they join peace talks, undermining recent diplomatic claims that the war in Bosnia-Herzegovina is all but over.

The injured man told doctors and journalists a mortar round had slammed into the yard of his high-rise apartment building as he worked in his garden and children played nearby.

But a U.N. spokesman, Maj. Rob Annink, said the blast was believed to have been from a hand grenade or other explosive device detonated at the scene of the injuries.

If the explosion was a mortar round, as witnesses at the front-line residential area claimed, it would constitute the worst violation of a six-week-old cease-fire that has nearly brought an end to the heavy artillery bombardment that terrorized Sarajevo civilians for 22 months.

In any event, Saturday’s explosion in the Alipashino Polje cluster of high-rise apartment buildings injured a 44-year-old man, his 7-year-old son and a neighbor’s 4-year-old child, inflicting a sobering reminder to Sarajevo’s 380,000 residents that war dangers have not completely subsided.

Most of the tanks, howitzers and heavy guns Serbian nationalist forces had used to pound the capital were moved or surrendered prior to a Feb. 21 deadline for withdrawal of artillery from a 12-mile radius of the capital. NATO had threatened to launch air strikes against any heavy weapons left within the exclusion zone, and Russian pressure on Bosnian Serb leaders compelled the rebels to mostly comply.

But hundreds of artillery pieces remain within the zone under the watch of overstretched U.N. forces and within easy reach of Serbian fighters still deployed near the weapons.

U.N. officials claimed that a sophisticated French radar system brought in to Sarajevo a month ago could precisely locate weapons firing in violation of the proclaimed truce. But in the case of at least two previous mortar blasts since the cease-fire, neither of which inflicted injuries, the firing positions were said by U.N. monitors to be untraceable or too close to the line of confrontation to allow retaliatory fire.

The Alipashino Polje area was a frequent target of Bosnian Serb gunners prior to the cease-fire. One theory among U.N. sources investigating Saturday’s blast was that an unexploded round had lodged in the garden and was inadvertently disturbed by the injured man or the nearby children.

Mines and unexploded ordnance have been a deadly problem throughout the Balkan war zones. On Saturday, a British peacekeeper was killed while preparing to detonate explosives that Bosnian government and Croatian forces had turned over to the United Nations as part of their bilateral cease-fire, officials said. The accident occurred near the town of Stari Vitez, in central Bosnia.

Conditions in Sarajevo have been markedly better since the cease-fire, despite the increasing violations, and a U.N.-brokered agreement Thursday to open some roads to limited civilian traffic next week has further spurred hopes that the siege of the capital might be drawing to an end.

But the ultimate success of the current truce depends heavily on enticing the Serbian rebel forces to cooperate in a new Muslim-Croat effort to rebuild Bosnia as a unified federation of three peoples--an aim openly rejected by the Serbs throughout the conflict.

Under pressure from their patrons in Serb-dominated Yugoslavia, the Bosnian Serbs may be compelled to take part in negotiations now being mediated by special Balkan envoys from the United States and Russia.

But diplomats close to the initial Muslim-Croat talks that took place at the U.S. Embassy in Vienna concede privately that the Serbs are interested in the negotiating forum only to gain international acceptance of their sovereignty over much of the land they have seized since rebelling against Bosnian independence in March, 1992.

Bosnian Serb leader Radovan Karadzic has already sought to barter his cooperation in the federation talks in exchange for lifting of U.N. sanctions that have beggared Yugoslavia, whose nationalist leaders have bankrolled the Serbian rebellion in Bosnia to gain territory for a Greater Serbia.

“We are ready to sign a peace agreement at any time, but we expect that all three sides would be treated equally, which includes the issue of the lifting of sanctions,” Karadzic was quoted as saying Saturday.

While the tenuous peace in Sarajevo showed signs of fraying, the recent reconciliation of Bosnian Muslims and Croats appeared to gain strength with the release of more than 800 prisoners of war captured by the two factions during the past year.

Bosnia’s Muslims and Croats, who together make up two-thirds of the country, initially fought side by side to defend Bosnian territory from the Serbian land grab. But they fell to fighting each other last spring after it became apparent that a Western-mediated peace settlement would be based largely on ethnic partitioning along the territorial status quo.

The International Committee of the Red Cross in Zagreb reported 500 Muslim prisoners released from Croat-run detention camps and jails, and 360 Croats freed from Muslim-held east Mostar and the town of Bugojno.

About 800 more POWs, reportedly the last held by the reconciling factions, were to be released in a few days.

But U.S. special envoy Charles Redman and Russian Deputy Foreign Minister Vitaly S. Churkin have underscored throughout their efforts to broker peace in Bosnia that the success of the new federation and hopes for ending the war hinge on the Bosnian Serbs.

Churkin told a Washington news conference that he believes the Serbs can be persuaded to cooperate with the Croat-Muslim federation agreement even if they choose to stay out of the federation.

He predicted that the Bosnian Serbs will eventually agree to reduce their own holdings from about 70% to about 50% of Bosnian territory.

Churkin bristled at suggestions that Russia is acting as an agent for the Serbs, with whom they share a Slavic heritage and Orthodox Christian religion.

Moscow, he said, “is bearing the burden of trying to find some common sense in the position of one party which is a very difficult party.”