Russian officials say terrorism was the cause of explosions that led to the near-simultaneous crashes of two Russian jetliners last week.

A top official of the Federal Security Service said that the crash of the two planes was "the result of a terrorist act."

The intelligence agency earlier announced that investigators had detected traces of a high explosive in the wreckage of the two crashed jetliners. However, it is the first time that Russian officials have publically speculated that the plane crashes were caused by explosions.

Last Tuesday, two Russian passenger planes carrying a total of more than 80 people crashed within minutes of each other, prompting concerns of a possible terrorist attack.

An Islamic group subsequently claimed its suicide attackers had brought down both planes to protest Russia's war on Chechnya.