US officials have warned international and regional airlines with flights to Russia of toothpaste tube bombs, say a report by CNN.

      According to the broadcaster, a bulletin was circulated among air operators urging them to inspect toothpaste tubes and cosmetics items for potential explosives.

      Despite the alert, “the authorities have increasing confidence about the safety of Sochi and the Olympic venues,” CNN quotes its source as saying.

      Security has been beefed up in and around Sochi, with multiple restrictions slapped on cars arriving in Sochi.

      In late December 2013, suicide bombers stages two terror acts in the southern Russian city of Volgograd, killing 34 and injuring more than a hundred people.