Dozens of brown bears searching for food have forced two villages in a mountainous region of southern Russia to impose a curfew, Russian news agencies reported on Monday.

The inhabitants of Yailyu and Bele would no longer be able to leave their villages without an armed guard during the day and must stay in their homes at night, the reports quoted officials as saying.

Bears have left the forest because of a lack of berries and nuts this year and have terrorised villagers for days, killing cattle, destroying fences and attacking people, RIA Novosti news agency said.

The two villages are located in an Altai mountains national park and the decision to impose the curfew "was taken by the park's scientific council," Sergei Varganov, the chief forest warden, was quoted as saying.

The reports said that up to 20 bears roam the two villages at night.