SIMFEROPOL, Ukraine -- The only television channel broadcasting in the Crimean Tatar language on the annexed Ukrainian peninsula of Crimea has stopped functioning along with its affiliates.

The ATR channel's owners said earlier that Russian media regulator Roskomnadzor had rejected several attempts by ATR to register under Russian law, citing various technicalities.

The deadline for registering the channel, which still holds a Ukrainian license to broadcast, was March 31.

The ATR media holding also includes FM radio stations Meydan and Lider, the children's television channel Lale and a news website, 15 Minutes. 

All of those outlets -- which broadcast in Tatar, Ukrainian, and Russian -- stopped operating as of April 1.

On March 31, Amnesty International called the Crimean Tatar media outlets' de-facto closure "a blatant attack on freedom of expression, dressed-up as an administrative procedure" and "a crude attempt to stifle independent media, gag dissenting voices, and intimidate the Crimean Tatar community."

Activists, community leaders, and rights groups say Crimean Tatars have faced discrimination, pressure, and abuse for their opposition to Russia's illegal annexation of Crimea from Ukraine in March 2014.