Last weekend, U.S. forces accidentally attacked a hospital in northern Afghanistan, killing at least 22 people, the top commander of U.S. and allied forces in Afghanistan said Tuesday, according to a report from the New York Post.

Gen. John F. Campbell told a Senate committee that Afghan forces requested U.S. air support while in combat with Taliban fighters in the Afghan city of Kunduz, the Post reported.

“To be clear, the decision to provide [airstrikes] was a U.S. decision, made within the U.S. chain of command,” Campbell was quoted in the article. “The hospital was mistakenly struck. We would never intentionally target a protected medical facility.”

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The medical facility that was struck was operated by the charity Doctors Without Borders, who called on Wednesday for an independent international fact-finding commission to be established to investigate the U.S. bombing of the hospital, which it deems a war crime.

"If we let this go, we are basically giving a blank check to any countries at war," MSF International President Joanne Liu told a news briefing in Geneva. "Today we say enough, even war has rules," she added.

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Defense Secretary Ash Carter said Monday the Pentagon is providing options to the White House, and Obama will be making decisions about future force levels later this fall, claimed the Post article, which added that Kunduz has been the scene of heavy fighting recently as its location on the Tajikistan border makes it an important hub for drug and gun smuggling.

Reuters contributed to this article.