A U.S.-based rights group said Saturday that China sentenced a writer to four years in prison last month for helping edit a magazine critical of policies in Tibet.

The International Campaign for Tibet said Tashi Rabten, the Tibetan editor of a banned magazine called Eastern Snow Mountain, was sentenced on June 2 in Aba, in China's southwestern province of Sichuan.

The ICT did not say what Tashi Rabten was charged with, but three other Tibetans who worked for the magazine were imprisoned last year on charges of inciting separatism.

The ICT says the magazine was the first published Tibetan language commentary about the situation following deadly anti-government riots in the Tibetan capital Lhasa in March of 2008.