MOSCOW: Russian President Vladimir Putin made an early morning call to his Belarusian counterpart Thursday, informing him that Moscow was launching a military operation on Ukraine, Alexander Lukashenko's office said.

"Around 5 am (0200 GMT) today there was a telephone conversation between the presidents of Belarus and Russia," Lukashenko's office said. "During the call, Vladimir Putin informed his Belarusian colleague about the situation on the border with Ukraine and in Donbas," added the office.

The Kremlin had no statement on the call.

Putin launched the offensive in the early hours of Thursday, after a surprise televised address.

NATO chief condemns Russia's 'reckless and unprovoked attack' on Ukraine

Ukraine's border guards said Thursday morning that the country is coming under artillery attack along its northern border with Russia and Belarus.

Russia has tens of thousands of soldiers stationed in Belarus, where it has held military drills.