MOSCOW, February 13 (RIA Novosti) - Ecologists have expressed fears that remnants of the U.S. and Russian satellites that collided on Tuesday could pollute a large portion of Russia, a federal environmental official said on Friday.

Konstantin Tsybko of the Federal Service for Supervision of Natural Resources said that a number of large ecological organizations had approached him since a U.S. Iridium satellite and the defunct Russian Cosmos-2251 collided approximately 800 kilometers (500 miles) above Siberia. This was the first time such an incident has occurred.

"Their fear is understandable, especially since the Western press has published reports that there could be a nuclear reactor on board one of the satellites," Tsybko said.

"You could imagine what would happen if part of the wreckage landed, for example, in Lake Baikal!" he said. "Therefore, in order to prevent any possible danger, ecologists have asked us to contact officially the appropriate departments to calculate the satellite wreckage's fall to Earth."