The suspect, identified only as "Jarosław A.," has been remanded in custody for three months following a court order, state broadcaster TVP Info reported.
According to Stanisław Żaryn, spokesman for Poland’s security services, the man was detained on July 11 in the country's southern Silesia region by the Polish Internal Security Agency (ABW).
"Jarosław A. ... was charged with signalling readiness to operate to the advantage of the Russian intelligence against Poland with the aim of transferring information, which could constitute a major injury for the Republic of Poland," Żaryn said in a statement in English.
He added that the suspect "planned to transfer a wide range of information to the Russians, including data concerning security and defence of Poland."
The suspect could face up to eight years in prison if convicted, according to the statement.
Source: PAP, tvp.info, gov.pl