The Catholic Archbishop of Moscow has expressed his 'deep sorrow' for the victims of the explosion on the St.Petersburg metro yesterday afternoon, in which at least nine people were killed and dozens injured.

Archbishop Paolo Pezzi offered his prayers and condolences following the deadly blast, and called for deliverance from 'the curse of terrorism' in Russia and around the world.

'With deep sorrow, I learned about the villainous terrorist act in St. Petersburg, which killed nine people and caused suffering and grief to many people," the archbishop said in a statement.

'Together with all faithful Catholics and believers of other faiths and religions, I turn to God with a burning prayer for deliverance of Russia and the world from the curse of terrorism,' he continued.

The explosion took place at around 2:30pm local time in a train carriage as it was passing through a tunnel between two underground stations.

Some reports indicated that the explosion may have come from a briefcase left on the train, and that it may have contained shrapnel.

The entire St. Petersburg metro system was shut down for an investigation to be carried out. Another explosive device was later found in the metro system and safely disabled.

The Russian Prime Minister Dmitry Medvedev called the explosion a 'terrorist act', while President Vladimir Putin, who was in St. Petersburg at the time of the attack, said all causes, including terrorism, are being considered.

Archbishop Pezzi called on the faithful to join him in prayer as the country mourns. 'Let the merciful Lord accept the dead in his arms, grant healing to the victims, consolation to the mourners. His blessing and help to all those who work to prevent the repetition of this tragedy,' he said.