Poland's conservative government says it rejected a multi-billion euro deal to buy Airbus military helicopters because it was bad for state security.

Poland ended negotiations with Airbus Helicopters last week over a 3.14 billion-euro ($3.5 billion) deal, straining ties with the French government, which partly owns parent company Airbus Group. Instead, Poland will buy Black Hawk helicopters made by U.S. company Lockheed Martin in Poland.

On Tuesday, Airbus Helicopters wrote an open letter to Poland's Prime Minister Beata Szydlo to protest the decision.

Defense Minister Antoni Macierewicz said the Airbus deal would have allowed the company to take over a servicing plant in Lodz, in central Poland, something the government was against. He spoke at the plant, where he and Szydlo assured workers they won't lose their jobs.