Unidentified armed men have managed to free Valeriy Bolotov, the 'people's governor' of the self-proclaimed Luhansk People's Republic, in a fierce fight with Ukrainian border guards near the Dovzhansky border checkpoint in Luhansk region, the Ukrainian State Border Service reports.

"Ukrainian border guards detained [Bolotov] at 0545, informed all law enforcement agencies about this, including those conducting an antiterrorist operation, and waited for assistance from security forces for about two hours, but nobody arrived," the Border Service told Interfax-Ukraine on Saturday.

Over 100 armed men managed to free Bolotov from detention in a fierce battle, it said.

"There are no casualties so far," it said.

The Border Service had told Interfax-Ukraine earlier on Saturday that Bolotov had been detained at the Dovzhansky border checkpoint while trying to enter Ukraine.

After informing Ukrainian law enforcement agencies of Bolotov's detention, the border guards put up a defense, as the checkpoint had been swiftly encircled by unidentified armed men.

"The checkpoint has been assaulted; about 100 armed men used grenade launches and hand grenades, and a battle is under way," the Border Service said.