An explosive device which accidentally did not go off was found in the centre of Sofia in the early hours of February 24 2009, the Interior Ministry said.

At 7.08am, the manager of Planet night club on Oborishte street, between Alexander Nevsky cathedral and Vassil Levski Boulevard, called the police about a suspicious package left outside the place.

Police immediately sealed off the area with the bomb squad sent in to secure the package. It was later identified to be an explosive device. Perpetrators have tried to set it on fire, but failed, police said.

If the 400 gram device had went off, it would have been one of the biggest blasts in Sofia's downtown. The results are hard to predict given that the traffic is extremely intense 24 hours a day in that area of the city.

Fortunately, the fuse failed to produce a flame and extinguished itself, police said.

This would have been the second blast outside a popular night club in Sofia in the past week.

An explosive device placed outside the entrance of Cafe Nero in Sofia's Ivan Vazov residential district went off soon after the restaurant closed in the early hours of February 18 2009.

No one was injured in the blast, which caused minor damage to surrounding buildings. The same as Planet night club, Cafe Nero, on Vitosha Boulevard and Yanko Zabounov Street, is noted in the neighbourhood for customarily being surrounded by clusters of dark-coloured luxury vehicles parked close to the entrance.