A group of Russian servicemen detained in eastern Ukraine did not get lost, but were carrying out a special task, Ukrainian National Security and Defense Council (NSDC) spokesman Andriy Lysenko has said.

"If the Russian elite forces are not competent with map reading, [and] cannot find their way on the ground, then there're no sense in mentioning other units and generals who send people to the east of Ukraine. We think that this is not a mistake, but a special task," he said at a briefing in Kyiv on Tuesday.

Earlier, a Russian Defense Ministry source told Interfax (interfax.ru) that Russian servicemen, detained by Ukraine, had crossed the Russian-Ukrainian border by mistake.

"Indeed, the named servicemen participated in patrolling a section of the Russian-Ukrainian border and, apparently, they crossed it by mistake at the unequipped and unmarked section. As far as we know, they did not offer resistance to the Ukrainian armed forced during their detention," the source said.