The World Health Organization headquarters building in Geneva. (Stefan Wermuth/Bloomberg)

A new congressional report claims that the World Health Organization’s guidelines on treating pain were directly influenced by the pharmaceutical industry, including a set of directions for prescribing powerful painkillers that appear to have been taken from opioid giant Purdue Pharma.

The investigation, from the offices of Reps. Katherine M. Clark (D-Mass.) and Hal Rogers (R-Ky.), points to evidence that pharmaceutical companies and those who profited from the increased prescribing of opioids aimed to push the WHO into endorsing use of the drugs across the globe. The WHO provides health guidance worldwide.

“The web of influence we uncovered, combined with the WHO’s recommendations, paints a picture of a public health organization that has been manipulated by the opioid industry,” according to the report, issued Wednesday.

Purdue said the company “strongly denies the claims” in the report, arguing that it “seeks to vilify the company through baseless allegations.” It said the company is based in the United States and has no international operations.

The World Health Organization did not respond to a request for comment Wednesday.

The report alleges that two WHO reports that provide guidelines for treating severe pain — one in adults and the other in children — draw directly from Purdue’s strategies on how to market opioids. The report cites Purdue’s 1996 budget plans, which were posted online by Kaiser Health News.

At the time, the WHO advised physicians to prescribe pain relief using a three-step system, starting with nonnarcotic pain relief, moving to an opioid designed for mild pain, such as codeine, and treating severe pain with a potent opioid such as morphine.

In the document, Purdue said one of its goals was to make OxyContin the opioid of choice for Step Two. The plan went on to say that the goal was to replace the powerful opioids typically prescribed in Step Three “by positioning OxyContin as the opioid to start with and stay with, thereby expanding the usage” of Step Two.

Five years later, Purdue’s 2001 budget plans said that OxyContin was “recommended and promoted” for Steps Two and Three in WHO’s ladder.

In a 2012 document on how to treat pain in children, the WHO did away with the three-step pain protocol in favor of a two-tiered approach that recommended starting a child on a nonnarcotic painkiller such as ibuprofen and then moving to a powerful narcotic if necessary.

“The benefits of using an effective strong opioid analgesic outweigh the benefits of intermediate potency opioids in the pediatric population,” according to the WHO document, titled “Persisting Pain in Children.” It also said that there is not a maximum dose of opioids for children.

Clark and Rogers’s report also alleges that Purdue’s marketing was based on the premise that prescription opioids were safe and effective and that addiction was rare, something the legislators claim the WHO also pushed in its guidelines.

Purdue is now the subject of a slew of lawsuits alleging that it engaged in the deceptive marketing of opioids, claims the company denies. The company pointed to a ruling by a North Dakota judge this month that dismissed a lawsuit against Purdue, ruling that the company’s labeling practices were consistent with federal regulations.

“While the findings in this report are tragic and alarming, they are unsurprising given this company’s unscrupulous history,” Rogers said in a statement. “The WHO must take action now to right the ship and protect patients around the world, especially children, from the dangers associated with chronic opioid use.”

The report claims that both Purdue and the WHO played down the risk of addiction, with the global health organization saying there was an “unreasonable fear” of opioids.

Clark said the investigation was sparked by a 2016 Los Angeles Times investigation of OxyContin that included a story on how a network of global companies owned by the family that controls Purdue, but not Purdue itself, wanted to sell the drug worldwide. Clark said she wrote WHO officials asking for information on the companies, but the agency never responded, prompting her to investigate.

“I think they have lent their credibility and their voice to the opioid industry,” Clark said.

The report says that many doctors and organizations that have ties to Purdue have aggressively pushed the use of prescription painkillers on the WHO. They include the American Pain Society and its global arm, the International Association for the Study of Pain. The report alleges that the IASP provided funding for the development of the WHO’s two pain guidelines.

The American Pain Society declined to comment. The International Association for the Study of Pain did not respond to a request for comment.

Clark said she wants the WHO to explain the guidelines and whether they were influenced by corporate strategy: “I think these guidelines need to be rescinded.”