Police are investigating possible terrorism charges

Itar-Tass said five adults and two children had been hospitalised and are all in a "satisfactory" condition.

One more male adult declined hospital treatment and went home, while a further injured person was being examined by medical staff.

Reports say the bomb, containing explosives equivalent to 200 grams of TNT, was placed under a bench at the station.

Television footage showed chunks of marble strewn on the station floor.

Members of the Federal Security Service sealed off the station after the explosion.

Trains kept running on the Ring Line, which serves Belorusskaya station, but did not stop there.

Traffic on the nearby Garden Ring, one of the city's main boulevards, came to a near standstill.

'Terrorist act'

Mayor Yuri Luzhkov, who visited the scene of the explosion, described it as "a 100% terrorist act".

The Moscow prosecutor's office said terrorism or other charges were being investigated.

Monday's explosion comes seven months after a blast tore through a central Moscow underpass, killing 13 people and injuring dozens more.

Mr Luzhkov blamed the August 2000 attack on Chechen rebels, but Chechnya's President, Aslan Maskhadov, had denied that rebel forces were involved.

Russian officials later conceded that that attack could have been linked to gang warfare rather than terrorist activity.