BEIJING—The International Monetary Fund is pressing China to disclose more information about its currency operations based on standards the Chinese central bank had pledged to follow, people familiar with the matter said, as Chinese authorities resort to more-discreet ways to support the yuan.

In recent months, the People’s Bank of China has turned to the derivatives market to help prop up the currency—a shift from its traditional approach of dipping into its dollar pile to buy yuan.

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