Vyacheslav Gladkov, governor of Russia's Belgorod region, said on Tuesday that the situation on the border with Ukraine was "difficult but under control."

"There is information that the enemy is trying to break through the border of the Belgorod region," Gladkov wrote on the Telegram messenger app.

"Our military is carrying out planned work. Please remain calm and trust only official sources of information," the governor said.

Russian Telegram channels with links to the security services said earlier on Tuesday that Ukrainian troops had attacked the border.