A US official on Tuesday dismissed as ridiculous claims by Russia that US ally Georgia committed genocide during fighting this month in two breakaway Georgian regions. US Deputy Assistant Secretary of State Matthew Bryza also demanded Russian action to end human rights violations in areas of Georgia occupied by its troops. Russia and Georgia have been exchanging accusations of atrocities in the conflict that has led to a major rift between Russia and Western countries. Georgia launched a heavy artillery barrage Aug. 7 on South Ossetia, a separatist Georgian province with close ties to Russia. Last week, Russian troops drove Georgian forces out of South Ossetia, and conflict also broke out in a second Russian-backed separatist region, Abkhazia. Russian prosecutors have opened a genocide probe into Georgian treatment of South Ossetians. Georgia sued Russia in international court, alleging murder, rape and mass expulsions of Georgians in both provinces.