Updated

Montenegro's government has rejected criticism from international watchdog groups over the months-long detention of an investigative journalist on charges of drug-trafficking.

The government said Tuesday the indictment and detention of Jovo Martinovic have nothing to do with his professional work and were the result of a criminal investigation.

Martinovic has probed crime and corruption for various media outlets. He was arrested in October last year on suspicion of "criminal association and illegal production, possession and distribution of narcotics."

Three human- and media-rights groups have demanded that Montenegro release Martinovic from detention, expressing concern it was motivated by his investigative journalism.

The Committee to Protect Journalists, Human Rights Watch and Reporters Without Borders said in a joint statement Monday Martinovic's case "violates his rights to liberty and due process."