In a letter to Uzbek Foreign Minister Vladimir Norov, Miklos Haraszti said all journalists should be free to collect and store information for publication.
He said that by interfering in the work of the journalists, authorities prevent a debate on matters of public interest.
Haraszti told RFE/RL that the OSCE has been in contact with Uzbek authorities about Niyazova's case.
"It is imminent now that the case is wrapped up by the judicial authorities in [Uzbekistan] and [Umida Niyazova's] case might be sent to the court," Harsazti said. "So, this is the moment when we practically issue the early warning typical for our institution, because we see now the imminent danger of her case being given to the court."
Niyazova was arrested in January and charged with illegally crossing the border and bringing "extremist literature" into the country.
The European Union's special representative for Central Asia, Pierre Morel, last month said the EU is closely following the case.
Uzbek and international rights groups claim the charges are politically motivated because Niyazova was interviewing witnesses of the violence in the eastern city of Andijon in May 2005.