BEIJING—Bitcoin can’t catch a break in China.

Chinese authorities ordered the closing of operations that create a large share of the world’s supply of bitcoin, tightening a clampdown that has already shuttered exchanges for the trading of cryptocurrencies in China.

A multiagency government task force overseeing risks in Internet finance issued a notice last week ordering local authorities to “guide” the shutdown of operations that produce, or “mine,” cryptocurrencies, according to the notice and people familiar with the information.

While the notice called for an “orderly exit” without setting a deadline, far-flung areas of China where cryptocurrency mining operations have flourished are complying. A local regulatory official in the far western region Xinjiang said Wednesday that his agency received the notice and is doing “what the country wants.”

The central bank, the lead agency in the task force on Internet financial risk that issued the notice, didn’t respond to a request for comment.