A senior Russian security official has admitted that a suspected bomb found at a block of flats in the town of Ryazan on Thursday was a dummy device placed there as part of a security exercise.

Discovery of the apparent bomb led police to evacuate the building in the middle of the night and bomb disposal experts were reported to have de-activated detonators and timers.

Now the head of the Russian Federal Security Service head, Nikolai Patrushev, has said on Russian NTV television, the exercise was carried out to test responses after over three hundred people were killed in recent bomb attacks on apartment buildings in Moscow and other cities. Mr Patrushev said similar exercises were being conducted in other Russian cities.