The Ukrainian National Security and Defense Council has confirmed the captivity of the commander of a military unit seized by militants in Donetsk in the small hours of Friday.

"Unfortunately, the military unit commander has been taken prisoner," Andriy Lysenko from the Ukrainian National Security and Defense Council information center said.

"Militants armed with guns and grenade launchers and mounted on combat reconnaissance patrol vehicles and armored personnel carriers attacked the military unit camp," he said.

The military unit personnel have been resettled. Negotiations are underway to free the commander, Lysenko said.