Censor.NET reports citing tvn24.pl.
The media say the detainee's name is Senior Lieutenant Piotr C, who has been on the wanted list since August 2016.
C. is suspected of transferring security information to Russia.
The Warsaw district military prosecutor's office has pressed charges against the detainee under part 3 article 130 -- collaboration with foreign intelligence, the media report.
The officer is said to have served in the 1st base of transport aviation in Warsaw and had access to secret access codes to the military base. In 2015, Piotr C. was transferred to reserve. The officer faces imprisonment of up to 10 years.