NATO Secretary General Javier Solana expressed his grief late Thursday at the death of the ethnic Albanians, but blamed Milosevic.

``A pilot from a democratic European country, believing he was attacking a military convoy, dropped a bomb on a tractor. We don't know how many people were aboard, but there were some dead,'' Solana said.

``Those people who were in the tractor were being chased from their homes by Milosevic's soldiers and police,'' Solana alleged. ``The person ultimately responsible for this tragedy has a name, he is called Milosevic.''

US President Bill Clinton said he regretted the bombings but casualties were ``inevitable'' in the fight against Serb atrocities. ``You cannot have this kind of conflict without some errors. This is not a business of perfection,'' he said. British Prime MinisterTony Blair said Milosevic was ultimately to blame. ``We are not going to take any lessons from Milosevic about care for refugees when these refugees are actually in a convoy because they are fleeing from the butchery, the savagery, the rape, the torture, the mutilation of ordinary innocent people,'' he said. NATO forces ``must strike and strike again'' at Yugoslav military assets, US Secretary of State Madeleine Albright had said and, as if on cue, NATO planes bombed the country in raids stretching from its northern border to the Adriatic coast, as the alliance's air campaign entered week four. For the first time the town of Subotica, 200 km north of Belgrade near the Hungarian border, was bombed. In Paracin, 110 km south of Belgrade, at least three NATO missiles landed early on Friday on a camp for Serb refugees from Croatia and Bosnia-Herzegovina, Tanjug news agency reported. There were no casualties, Tanjug said, explaining that inmates had taken refuge in air-raid shelters.

Montenegro, Serbia's smallerpartner in the Yugoslav federation, was also targeted for the first time in more than a week. Several explosions were also heard early Friday on the outskirts of Belgrade, accompanied by heavy anti-aircraft fire. Tanjug reported that NATO had damaged a bridge over the Danube about 50 km southeast of the capital. Two missiles struck the bridge linking the towns of Smederevo and Kovina about 50 km southeast of Belgrade, Tanjug said, making it impassible. The bridge is the fifth on the Danube to have been destroyed or targeted since the start of the NATO airstrikes, halting international barge traffic along the river.

In Albania, two civilians were wounded, one of them seriously, when Serb shells crashed into the village of Kolsh on the border with Kosovo, the interior ministry in Tirana said.

The village, 10 km from the town of Kukes where more than 100,00 Kosovar Albanians have taken refuge, was hit by five shells late Thursday. The village lies 500-600 meters inside the border. Meanwhile, the exactdetails surrounding an air strike on a refugee convoy in western Kosovo remained unclear. Though NATO admitted to a mistaken bombing, the Pentagon said it was unclear whether the attacks caused civilian casualties.

Televised videotape showed a scene of carnage on a road between the towns of Prizren and Djakovica where Serb officials said as many as 75 people were killed by NATO air strikes.

NATO officials in Brussels admitted that a civilian vehicle was hit by a NATO weapon, but it was unclear if that attack was at the same location. Belgrade meanwhile demanded an immediate meeting of the UN Security Council but the request was refused.