Poland has arrested a Spanish national of Russian origin on suspicion of participating in foreign intelligence activities, the Internal Security Agency (ABW) said on Friday.

The man, identified as an agent of Russia's military intelligence agency (GRU), was detained in Przemysl - near Poland's border with Ukraine - on the night of Feb. 27-28, ABW said in a statement.

The agency said the man carried out operations to benefit Russia, and travelled in Europe and elsewhere under cover of being a journalist.

"Before his detention, he was planning to go to Ukraine in order to continue his activity," it said.

The man will remain in custody for three months initially, and faces up to 10 years in prison if found guilty, the agency said.