Congressional investigators have determined that several top NFL health officials attempted to influence a major government research study on football and brain disease, reports ESPN’s Steve Fainaru and Mark Fainaru-Wada.

The NFL reportedly pressured the National Institutes of Health to move $16 million given to a Boston University researcher and reallocate the funds to a member of the league’s committee on brain injuries. The study had initially been a part of a $30 million “unrestricted gift” by the league to the NIH.

The NFL’s actions violated rules preventing private donors from meddling in NIH peer review, ESPN reports.

In December, the NFL backed out of a signed agreement to pay for the study, which instead put the cost on taxpayers. The NFL reportedly backed out of the study because the NIH would not remove renowned Boston University researcher Robert Stern, who has criticized the league in the past, from the project.

The NFL later offered to pay $2 million, but the NIH turned down the league’s offer.

“In this instance, our investigation has shown that while the NFL had been publicly proclaiming its role as funder and accelerator of important research, it was privately attempting to influence that research,” the congressional report says, according to ESPN.

After pulling their funding, the NFL looked to spend its $16 million on another project that would involve members of the league’s brain injury committee, ESPN reports. The NFL did not want this proposed project to be subject to peer review by the NIH, according to ESPN. The idea was rejected by NIH director Francis Collins.

The congressional report comes as the league faces increased scrutiny over its handling of brain trauma. The neurodegenerative brain disease chronic traumatic encephalopathy, or CTE, has been linked to football and has been diagnosed in a number of deceased NFL players, including Junior Seau, Dave Duerson and Ken Stabler.

The disease, which can cause memory loss, depression, dementia and a host of other symptoms, can only be diagnosed posthumously.

The NFL has repeatedly denied withholding funding from the NIH study because of Stern’s criticisms.

Jeff Miller, NFL executive vice president of health and safety, told investigators that the NFL voiced its concerns appropriately. Miller is the same official that testified before the House of Representatives and acknowledged a link between football and degenerative brain disorders like CTE.

The full congressional report can be read here.