Unlawful armed units are building a stronghold near Kominternove, a community close to Mariupol in Donetsk region, which they have occupied and are actively mining roads and approaches to it, says Andriy Biletsky, the commander of the Ukrainian National Guard's Azov regiment.

"The community was seized yesterday in the morning by approximately one or two companies supported by light and heavy armored vehicles; that is, up to 12-15 armored vehicles have been sent there," Biletsky said in a telephone interview with TV Channel 24 on Tuesday.

"Artillery reserves have also been brought in, and they have started building the first stronghold opposing the Ukrainian side near Kominternove. They are laying concrete, have brought construction equipment, and have started actively mining roads and approaches," Biletsky said.

"Therefore, I think they have seized the village in earnest and for a long time," Biletsky said.

He described the surrender of Kominternove as the Ukrainian government forces' great tactical mistake, as this threatens their positions in Shyrokyne and Pavlopil.

"There is no point in making forecasts about whether there is going to be an offensive or not. What we can say with a hundred percent certainty is that the separatists have significantly improved their positions for launching an offensive," he said.

The Ukrainian military had said earlier that, on Tuesday morning, militants had seized Kominternove, which is located within the so-called gray zone, opened fire at the Ukrainian armed forces, and refused to admit OSCE Special Monitoring Mission members to the area.