The explosion shook buildings several kilometres away

There were no reports of deaths or injuries and officials said they did not suspect an act of terrorism.

A spokesman for the local subsidiary of the gas company Gazprom said supplies to Russian and foreign customers would not be disrupted.

The main pipeline for Russian gas lies well to the south of the blast, but a pipe supplying Finland is nearby.

Witnesses said the massive explosion, at just after midnight on Wednesday (2000 GMT) in St Petersburg's northern suburbs, shook buildings several kilometres away.

There was a traffic jam as hundreds of frightened residents fled the area but AFP news agency said the fire was put out after two hours.