Who is to blame? What Russia can do Timeline: The blasts which shook Russia

The blast occurred in a block of flats in Bolshaya Cherkizovskaya street in the north of the Russian capital.

Russian news agencies quote police sources as saying it was caused by a five litre gas cylinder.

The injured have been taken to hospital. The blast shattered some windows and a floor in one section of the building is reported to have collapsed, according to the Interfax news agency.

Emergency services are at the site of the explosion.

Bombings

The explosion follows a series of terrorist bomb attacks on residential flats in the city which have killed about 300 people.

This is the fourth blast in Moscow in addition to others around the country. The Russian Government has blamed the attacks on Islamic rebels from Chechnya and Dagestan.

The attacks have led to widespread panic and a security crackdown. Police presence on Moscow streets has been increased and frequent checks are carried out throughout the city.

Correspondents say there is a growing hostility directed against Chechens and other ethnic minorities living in Moscow.

Chechen authorities denied that they have had anything to do with the bombings.