MOSCOW, July 29: A powerful explosion destroyed an oil company building in central Russia on Monday, killing at least 15 people and injuring 15, officials said.

As many as three people remained trapped under the rubble of the two-storey building late Monday despite day-long efforts by rescue workers and specially trained dogs, the Ministry for Emergency Situations said.

Officials said a natural gas cylinder exploded in the kitchen of the Lukoil-Permneft company building in the Ural mountains.

Investigators couldn't immediately say what caused the tank to blow up, said a Ministry spokesman who declined to give his name.

Rescue efforts were expected to continue through the night, he said. The workers pulled a dozen or more survivors and several bodies from the rubble.

Copyright © 1997 Indian Express Newspapers (Bombay) Ltd.