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.

It is understood a street  has been closed off.

Reports suggest 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".