At least 20 people are reported to have been killed in an explosion at Moscow's Domodedovo airport.

Reports have suggested a suicide bomber was responsible.

Russian news agencies cited unspecified sources as saying the blast occurred inside the airport's international arrivals hall.

The Russian state news agency has said 23 people have died and around 130 people are thought to have been injured.

Security has been stepped up across Moscow following the deadly explosion, Sky News reported.