"We cannot say that the planes were hijacked on the basis of information from flight recorders. The flight data shows nothing but disintegration of the planes," said Levitin who is leading a commission investigating the tragedies, the Interfax news agency reported.

    Two Russian passenger jets, Tu-134 and Tu-154, crashed almost simultaneously Tuesday night after taking off from Moscow's Domodedovo Airport, killing all 90 people on board the two planes.

    Earlier reports said the Tu-154 sent hijack warning signals before it crashed.

    But Levitin said the plane's pilot had not pressed the alarm button before the crash and the mayday came several seconds after the plane's disintegration, possibly due to a short circuit following the breakup.

    Levitin said late Sunday that the crashes were most likely caused by terrorist attacks. An Islamic group vowing support for Chechen rebels claimed responsibility for the twin crashes.

    Traces of explosives were detected on the wreckage of both planes and investigations have been focused on two Chechen women --one on each plane.

    Levitin said neither of the planes' pilots performed incorrectly and that neither had time to report anything amiss before they disappeared from radar screens. A preliminary conclusion can be drawn that both planes disintegrated at cruisingaltitude.

    The minister noted that the investigation commission has finished the first phase of its technical probe and said he believes it will take about six weeks for the commission to reach its primary conclusions.