Police have confiscated 800 grams of explosives and a hand grenade from a passenger on a bus en route to Moscow, the Interior Ministry said.

The bus was brought to a halt on Thursday afternoon at 458 kilometers into its journey from the Stavropol region. One of the passengers, a 30-year-old man, was found harboring nine blocks of TNT and a hand grenade in his luggage, police told Interfax Friday.

A criminal case has been opened against the detained man on charges of illegal possession of firearms and explosives, which carries a sentence of up to four years in prison.

Russia has been on high alert following a suicide bomber's attack on a city bus in Volvograd Monday, which claimed the lives of six people.