GENEVA—The United Nations’ human rights office is finalizing its assessment of the situation in China’s Xinjiang region, where Uyghurs are alleged to have been unlawfully detained, mistreated, and forced to work, a spokesperson said on Friday. Rupert Colville said that the office of U.N. High Commissioner for Human Rights Michelle Bachelet hoped to publish its report in the coming weeks and that there had been “no concrete progress” in long-running talks with Chinese officials on a proposed visit. Earlier on Friday, an unofficial British-based tribunal of lawyers and campaigners said Chinese leader Xi Jinping bore primary responsibility for what it said was genocide, crimes against humanity, and torture of Uyghurs and members of other minorities in the Xinjiang region. The Chinese regime dismissed the tribunal, which has no powers of sanction or enforcement, as a “farce”. “The Uyghurs tribunal has brought to light more information that is deeply disturbing in …