The Paris-based group reporters without borders (RSF) said that Ogulsapar Muradova, a local correspondent for the US-funded Radio Free Europe/Radio Liberty (RFE/RL) and Annakurban Amanklychev of French production company Galaxie-Presse, were sentenced to six years in jail on Friday.
The trial, which RSF called "absurd, unjust and disgraceful" lasted for two hours without any independent observers present, it said. The Turkmen authorities could not be reached for comment.
RSF said that the trial of the three had been "orchestrated by President-for-Life Saparmurat Niyazov".
RSF said: "Niyazov himself decides what prison sentences are to be handed down in a country where press freedom does not exist under a regime that is one of the most brutal in the world towards the media."
RFE/RL said on its website (www.rferl.org): "In a June 19 televised address ... National Security Minister Geldymukhammed Ashirmukhammedov claimed to have foiled an alleged foreign-funded plot to destabilise the country.
"Ashirmukhammedov said that the purported conspiracy also involved a number of Western diplomats. Yet, none of these allegations ever re-surfaced in the run-up to the trial."
The three, who were arrested in June, worked for the international Helsinki federation for human rights.