Facebook recently investigated research around suspicious content on its platform meant to support the campaign of Democratic presidential candidate Sen. Bernie Sanders (I-Vt.), the Wall Street Journal reported Monday.

The newspaper, citing unnamed sources, reported that top executives at Facebook were notified of the investigation, which was sparked by two independent outside researchers who told Facebook they found evidence that pro-Sanders content was being circulated by Russian agents and Trump supporters.

A Facebook company spokesperson pushed back against the WSJ article, telling The Hill in statement that the company has not been able to validate the claims made by researchers.

“We welcome and regularly receive reports from the research community,” the spokesperson said. “We investigate each credible claim we receive, just as we did in this instance when an outside researcher contacted us. To date, we have not been able to substantiate the researcher’s claims and we have not been notified by the intelligence community.”

The spokesperson added that “had we found a campaign of coordinated inauthentic behavior, we would’ve removed it and announced it publicly, just as we did more than 50 times last year.”