Monday, May 29, 2006 12:19 PM

BELGRADE, Serbia-Montenegro-A blast ripped through an explosives' factory near Belgrade on Monday, killing at least four people and injuring three, Serbia's interior minister said.

The explosion shook the area around Baric, some 30 kilometers (18 miles) southwest of the capital. Police and soldiers sealed off the Prva Iskra chemical plant, which produces explosives, including TNT, as well as toxic hydrofluoric acid, used as a component for household detergents, Interior Minister Dragan Jocic said.

Police said that the blast occurred in the part of the factory that produces explosives, not toxic chemicals. Investigation was under way to determine cause of the blast.

Serbia's Environment Minister Aleksandar Popovic said the blast "has not caused any chemical spill ... there is no danger of pollution.'"

Initially kept from entering the factory because of fears of more explosions, medics were eventually allowed into the compound and took the injured to a Belgrade hospital.

During NATO airstrikes against Serbia in April 1999, the plant was targeted several times because it was believed to produce explosives and chemical warfare agents, including sarin and mustard gas.