
An armed group has crossed from Ukraine into Russia's Belgorod region and clashes there have injured a number of people, Russian authorities say.
Local governor Vyacheslav Gladkov said Russian forces were searching for "saboteurs" who, he said, had attacked Grayvoronsky district by the border.
Vladimir Putin's spokesman said the Russian president had been informed.
Ukraine denies responsibility and said Russian citizens from two paramilitary groups were behind the incursion.
Mr Gladkov said eight people had been hurt, including two people admitted to hospital after a village was shelled and three people who were hit by shrapnel in the town of Grayvoron.