WASHINGTON — The World Bank said on Monday that it would scale back development work in China’s Xinjiang region after speculation that a $50 million loan it granted in 2015 for an education project was being used to fund Muslim detention camps.

The bank has been conducting a review of the project since Senator Marco Rubio, Republican of Florida, and Representative Jim McGovern, Democrat of Massachusetts, expressed concern about it in August and after an independent researcher found evidence suggesting that funds were being used to buy police batons and tear gas launchers.

The Chinese government has been facing criticism for detaining more than a million Muslim Uighurs and placing them in “re-education” camps where they are forced to renounce their religious beliefs and embrace the ideology of the Communist Party.

The bank said it had conducted an extensive review of the project and was not able to substantiate the allegations. However, the bank acknowledged the challenge of rigorously monitoring the situation and said it was making changes to the project.