SARAJEVO, Bosnia-Hercegovina -- Government defense forces exchanged fire with Serbian guerrillas Tuesday and dug into positions in several Sarajevo hilltops and residential neighborhoods captured in bloody street-to-street assaults aimed at breaking the blockade of the capital by insurgent Serbian fighters, officials said.
Serbian gunners fired fresh, intermittent shellfire into what was once one of the most pictureque cities in the Balkans from positions around Sarajevo airport and a Yugoslav army base in the suburb of Lukavica.
Yet the shellfire was nowhere near as intense as the previous four days, when Sarajevo was pummeled by the longest and most destructive barrages of the more than two-month-old Serbian offensive to rip a self- declared Serbian state out of the newly independent former Yugoslav republic.
'It's heaven today compared to yesterday,' said an official at the U.N. Protection Force headquarters.
There were no fresh details on casualties from the bombardments and street-to-street fighting that raged for 18 hours Monday after security forces launched a massive multi-pronged drive to break a more than month-long Serbian seige that has brought the city of 560,000 to the brink of starvation.
On Monday, officials at three hospitals said that at least 20 people were killed and 344 injured, bringing the total for two days to 51 dead and almost 760 others wounded.
Dragan Marijanovic, a Defense Ministry spokesman, conceded that the battles had been costly for the city's defenders.
'We have had large losses in infantry,' he said. 'Both sides are counting their dead.'
The relative lull in fighting came hours after the U.N. Security Council in New York authorized the deployment of a 1,000-man contingent to secure the Serb-held city airport for flights of desperately needed humanitarian aid.
Officials said that Bosnian defense forces had consolidated positions seized in several residential areas and on strategic hilltops from which Serbian gunners had been blasting shellfire into the city almost daily.
Bosnian fighters, who are predominantly Muslim Slav, but also include Croats and loyalist Serbs, succeeded in driving Serbian fighters from Zuc hill, which overlooks the western edge of the city.
The assault was backed by covering fire from four 155mm howitzers the Serb-dominated Yugoslav army surrendered as part of an agreement for a withdrawal from Sarajevo that it completed last Friday, officials said.
Officials said Bosnian fighters also advanced up Hrasno hill -- a residential area on the opposite side of the Miljacka River from Zuc -- but were unable to capture an abandoned Yugoslav army barracks taken over by Serbian Democratic Party guerrillas.
'Up on the hills is real hell. But, we must try to retake them,' said Mirsav Tokaca, a commander of the units that pushed up Hrasno. 'We have to advance another 100 meters. They have three machine gun nests. It is difficult to approach them.'
The neighboring Mojmilo hill was also secured by Bosnian fighters in the first phase of an operation to drive Serbian units from positions encircling the Mojmilo and neighboring Dobrinja apartment complexes and free tens of thousands of residents from sieges and point-blank artillery barrages.
Officials said security units moved into the Vidikovac area of Trebevic hill, located to the southeast of the city center, on top of which Serbian forces maintain artillery batteries near the bob sled run built for the 1984 Winter Olympics.
The capture of Vidikovac would allow Bosnian fighters to sever road links between the Serbian Democratic Party headquarters town of Pale, 5 miles east of Sarajevo, and the Yugoslav army garrison at Lukavica, on the capital's western fringe, officials said.
Defense forces advances were also reported through residential areas on the lower slopes Vraca hill, which overlooks the city center. The drive there is aimed at silencing Serbian mortars entrenched in an Interior Ministry training center located on a rocky promenade less than a mile from the presidency building.
Police said that in Monday's battles, security forces captured 10 Serbian armored personnel carriers, six tanks and a number of canons and mortars.
Serbian Democratic Party leaders have claimed 70 percent of multi- ethnic Bosnia-Hercegovina for their self-declared state, which they want to merge with the Serb-dominated Yugoslavia forged on April 27 by communist-ruled Serbia and its tiny dependent, Montenegro.
Serbian forces, which were armed and backed by the Yugoslav army, have seized much of the territory they claimed and refused to halt their offensive despite the imposition of sweeping U.N. economic sanctions on May 31 against Serbia and Montenegro.
Communist President Slobodan Milosevic of Serbia is widely regarded as the chief architect of the Serbian offensive that began in Bosnia- Hercegovina in the runup to international recognition in early April of the republic's independence from the wreckage of former Yugoslavia.
The Yugoslav army says it has withdrawn from Bosnia-Hercegovina all soldiers who are native to Serbia and Montenegro. But it left for the Serbian Democratic Party vast stocks of weapons and up to an estimated 80,000 Serbian troops who are residents of the republic.
In addition, the Serbian 'army' is commanded by Yugoslav army Maj. Gen. Ratko Mladic.
Most of the republic's 1.4 million Christian Orthodox Serbs opposed independence and demand the right to join the two-republic Yugoslavia.
The 1.9 million Muslim Slavs, most of the 750,000 Roman Catholic Croats, and many moderate Serbs support the republic's territorial integrity.
More than 5,000 people have been killed and 22,000 injured in the war, which has left scores of towns and villages devastated. More than 1.3 million people have been driven from their homes.
