Black box found in Russian plane crash   

    Traces of explosive have been found on the wreckage of the second of two Russian passenger planes which crashed almost simultaneously this week, Russia's Federal Security Service (FSB) said Saturday.

    FSB spokesman Sergei Ignatchenko told reporters that investigators had found hexogen on the wreckage of a Tu-134 jetliner which crashed in the Tula region south of Moscow on Tuesday night.

    His announcement came one day after a previous one which reported similar explosive materials on the wreckage of a Tu-154 that went down in the Rostov region in southern Russia almost simultaneously with the Tu-134.

    Ignatchenko called the crash of the Tu-154 as a "terrorist act".

    The Tu-134 and Tu-154 crashed almost simultaneously after taking off from Moscow's Domodedovo Airport, killing all 90 peopleon board and raising fears of terrorist attacks.

    "Under instructions from the Russian president, the FSB is studying international experience of combating terrorism on air transportation," Ignatchenko said.

    He said Russia was planning to use the Israeli flight security system, considered the best in the world.

    The tragedies came five days ahead of Sunday's presidential election in Chechnya, a breakaway republic of Russia. Separatist rebels there have been blamed for a series of terror activities that have claimed hundreds of lives.