China is adding to bond investors' jitters as traders brace for what they fear could be the end of a three-decade bull market.

Senior government officials in Beijing reviewing the nation's foreign-exchange holdings have recommended slowing or halting purchases of U.S. Treasurys, people familiar with the matter said Wednesday.

The news comes as global debt markets were already selling off amid signs that central banks are starting to step back after years of bond-buying stimulus. Yields on 10-year U.S. Treasurys rose for a fifth day, touching the highest since March.