Chinese officials are planning to put Tashi Wangchuk, who advocates broader Tibetan language education, on trial next week for “inciting separatism,” a charge that could result in a sentence of up to 15 years in prison, according to his lawyers.

Mr. Tashi, 32, has been detained for nearly two years in and around the town of Yushu, on the Tibetan plateau in the far west of China. He is among the most prominent political prisoners in China. The police took him from his home in January 2016, two months after he appeared in a New York Times video and article about Tibetan language education. Mr. Tashi had also written blog posts on the subject.

International human rights supporters and Tibet advocacy groups denounced the upcoming trial after Liang Xiaojun, one of Mr. Tashi’s lawyers, wrote online this week that officials at the Yushu Intermediate Court in Qinghai Province had scheduled Mr. Tashi to appear in court on Thursday. One rights advocate, Michael Caster, said on Twitter that the case was “a travesty.”

Communist Party officials generally decide the outcome of political trials in China; the accused is almost always convicted and sentenced to prison.