Qinghua Mohammad said, “If a case would have been made against them, an investigation would have been carried out with the help of the relevant authorities without discrimination.”

The case against the three men came when prosecutors charged them in January with charges related to crimes committed when they were students in a university in the city of Chengdu.

Authorities have not said where the three men are now.

Beijing is the world’s biggest exporter of natural resources, but has struggled in recent years to provide basic services such as electricity and water to cities such as Beijing. But efforts have been made to upgrade some cities and upgrade infrastructure.

Some 40,000 people from the western region of Xinjiang, home to some 10 million people, have set up protest camps in recent years. Rights groups say violence against these people remains a major problem in many parts of Xinjiang.

(Additional reporting by Ben Blanchard and Eric Walsh in Beijing; Editing by Chris Reese, Leslie Adler)

Our Standards: The Thomson Reuters Trust Principles.

The Trust Principles are a set of principles established in 1968 under the World Bank arm of the United Nations, which describe a framework for promoting economic prosperity with effective regulation of the financial system in emerging economies.