British officials believe Russian authorities were behind a plot in October to kill Montenegro's pro-Western prime minister, the Sunday Telegraph newspaper reported, citing senior British government sources.

A special prosecutor in the former Yugoslav republic said in November that a group of "Russian nationalists" had planned to assassinate Prime Minister Milo Djukanovic to get an opposition party into power.

Moscow denied involvement in any plot, and Montenegrin opposition parties have said the plot was fabricated and accuse Djukanovic of using the security services to help extend his quarter century of dominance.