Portugal's public prosecutor has brought charges of espionage, disclosing state secrets and corruption against a Portuguese spy and a Russian secret service agent.
The prosecutor's office alleges the Portuguese Security Intelligence agent met with the Russian in Rome last year and handed him secret documents in return for €10,000.
The Portuguese spy was under suspicion and was being secretly followed in Rome by Italian and Portuguese officials, Thursday's statement said. It provided no details about the secret documents or the Russian's identity.
Portugal is a member of Nato and the European Union and the two men were arrested in Rome.
The Portuguese spy is in custody in Lisbon but an Italian court refused to extradite the Russian, who was freed, the statement said.
His whereabouts are not known.