Three women and a man took part in the suicide bomb attack that killed at least 40 people and wounded scores on a Russian commuter train packed with school children and students near war torn Chechnya today.

A SUSPECTED member of a Chechen gang was arrested in Moscow while carrying nearly 18lb of mercury, and authorities believe he intended to use the poison in a terror attack, police said yesterday.

Facing growing criticism of the secrecy surrounding how the Moscow theatre siege was ended, Russian officials today showed off explosives and other evidence found at the scene.