KYIV (Reuters) - Ukraine's military said on Thursday it had destroyed four Russian tanks on a road near the eastern city of Kharkiv, killed 50 troops near a town in Luhansk region and downed a sixth Russian aircraft, also in the country's east.

       Russia has denied reports that its aircraft or armoured vehicles have been destroyed.

       Ukraine's border guard service said that three of its servicemen had been killed in the southern Kherson region and that several more were wounded.

       (Reporting by Natalia Zinets and Matthias Williams; Writing by Tom Balmforth; Editing by Alison Williams)