"We are concerned at the progressive militarisation of this country," foreign ministry spokeswoman Maria Zakharova said, adding that "the signing of a contract to supply the American Patriot system served as recent confirmation for this".

Poland has signed an offset deal with the United States ahead of a final agreement to buy a Patriot anti-missile system, Defence Minister Mariusz Blaszczak said Friday.

"Warsaw is increasing its spending on defence and making serious efforts to achieve military and technical modernisation of its national armed forces. It is reforming the system of managing troops and increasing troop numbers," Zakharova said at a press briefing.

Moscow sees these moves as an "element of destabilisation of the military and political situation in Europe and an a threat to Russia's national security," Zakharova said, while stressing that the country's "defence resources are sufficient to ensure the impregnability of our borders and the protection of our territory."

The Patriot is a mobile air-defence system designed to intercept tactical ballistic missiles, low-flying cruise missiles and aircraft.

Moscow has in the past criticised plans to deploy the US Patriot missile system in Poland and Romania, calling this a breach of an arms control treaty signed in 1987.