An explosion heard in central Stockholm is likely to have been caused by a gas leak.

The blast occurred at 11:40am local time in the area around Brännkyrkagatan on Södermalm, according to witnesses.

The street has been blocked off. Police have arrived at the scene.

RT reports that no one has been hurt, and that authorities "suspect it was a gas leak."

Initial reports in local media said witnesses described the blast as "powerful".

Where the explosion was heard (Google)

Police have said there are "no signs of a crime" and that the incident is likely not as large as first feared.

The owner of the apartment where the blast happened has been contacted by local authorities.

Police spokesman Albin Birch bark Berg has said: "We are there to investigate what happened, but at present it is unclear."

A window of a nearby apartment has been shattered, although it is now thought to be unrelated to the explosion.