Ukrainian army units which had been trapped by pro-Russian armed men on the border with Russia broke out of the blockade on Friday, Aug 8 and rejoined government forces, but 15 soldiers and border guards were killed in the operation, the Ukrainian military said, according to Reuters.

Military sources quoted by Ukrainian media said Ukrainian units had been effectively encircled by the militias on a section of the border with Russia south of the town of Luhansk and east of the main regional city of Donetsk.

After government forces opened up an escape corridor, the trapped units were able to force their way out, military sources quoted by the media said.

"Seven service staff and eight border guards were killed and 79 injured," military spokesman Andriy Lysenko told journalists.

The latest military deaths push the death toll among government forces alone to more than 400.