Russian forces killed a group of five saboteurs who breached the country’s southwest border from Ukraine on Monday, news agencies quoted the military as saying, in an accusation that Kyiv dismissed as the latest in a series of fakes. The accusations escalated already soaring tensions over a Russian military buildup. Kyiv and the West fear that a border incident near eastern Ukraine could be used as a pretext for Moscow to attack its neighbour. Russia denies such plans. Russia’s rouble fell to its weakest against the dollar since Jan. 27 on the reports, which quoted a statement from Russia’s So…