A number of other rights groups, including Amnesty International and Reporters Without Borders, have also expressed concern.
The two -- Meret Khommadov and Jumadurdy Ovezov -- were arrested in Turkmenistan's Mary region on March 7.
Neither their families nor Radio Free Europe/Radio Liberty have been able to obtain information about the two.
Amnesty called on Turkmen authorities to refrain from torturing the journalists. The group said the authorities are under an obligation to reveal the journalists' whereabouts and give them access to legal counsel.