Are mercenaries from Poland fighting in Eastern Ukraine?

According to a source within the Interior Ministry of Ukraine, as broadcasted on Russian news agency RIA-Novosti, Arsen Avakov and Valentin Nalivaicenko asked for an emergency procedure of an issue of 300 passports for citizens of Poland and other Baltic countries, former Soviet Republics.

It's estimated that these mercenaries' officers will act as local commanders and military advisers to the military operation, which Kiev has unleashed against the rebel cities of eastern Ukraine. The same source mentions that actually the "interested parties" for Ukrainian passports are already operating in the Eastern Ukraine. Related numerous testimonies recently recorded and concern both calls via radio, made in English, and understandings between armed soldiers, who, as residents noted, don't react and don't understand either Russian or Ukrainian.

To these complaints the Russian Foreign Ministry has sought an explanation from the American side, as no company mercenaries can act in foreign territory, unless it has permission from the State Department. So far Russia characterizes the answers and explanations of Washington "vague" and generates the impression that the American leadership wants to hide something thoroughly.