The IRS confirmed in a letter it is looking into claims of “pay-to-play” practices at the Clinton Foundation, after dozens of Republican lawmakers requested a review of potential “criminal conduct” at the organization founded by the family at the center of this week’s Democratic National Convention.

Commissioner John Koskinen wrote in a July 22 letter to Republican Rep. Marsha Blackburn that the issue has been “forwarded” to the IRS “Exempt Organizations Examinations” program in Dallas.

“This program considers all referrals and will send you a separate acknowledgement letter when it receives your information,” he wrote, in a letter first reported by The Daily Caller.

It’s unclear whether the agency might take any further action. The letter noted that, under the law, they could not reveal “any actions we may take on this information.”

A Clinton Foundation source, though, rejected reporting that the letter indicates an investigation.

“Nowhere does this letter say that there’s an investigation, or that the IRS is even considering an investigation,” the source said.

Asked for comment on the referral, the agency said in a statement: “The IRS receives referrals from a variety of sources. We forward all referrals to the appropriate area for consideration of whether there are issues that justify further review. We have standard processes and procedures we follow when we receive information or referrals from outside groups. Due to federal privacy protections, the IRS cannot comment on individual taxpayers or organizations.”

The request for an examination came in a July 15 letter from 64 House Republicans including Tennessee Rep. Blackburn. In the run-up to the Democratic convention where Hillary Clinton was nominated for president Tuesday, they asked the FBI, IRS and Federal Trade Commission to examine the dealings of the foundation.

"From the information we have been able to gather, it appears the Clinton Foundation is a 'pay to play' sham charity that needs to be investigated," Blackburn said in a statement on Tuesday. "The Clintons have used their Foundation to personally enrich themselves at the expense of American foreign policy. At a minimum, the Foundation’s tax-exempt status needs to be reviewed and revoked immediately."

As reported Monday by FoxNews.com, their letter focused primarily on three unresolved controversies, brought up by Peter Schweizer’s book, “Clinton Cash” and New York Times reporting in 2015. They involve the inconsistencies with the foundation’s initial 501(c)(3) filing; the sale of a company called Uranium One; and the Clintons’ ties with Laureate International Universities, a for-profit education company.

“The foundation has routinely gone behind its pledge to act in furtherance of charitable causes and beyond that scope of activities indicated in its initial filings with the IRS,” the letter says. “The appearance of ‘pay to play’ transactions involving Laureate and Uranium One also raise serious allegations of criminal conduct requiring further explanation.”

Hillary Clinton’s presidential campaign blasted the members for seeking an additional probe.

“This is another baseless political attack from House Republicans who just spent two years and $7 million of taxpayer money on the sham Benghazi Committee and are now just regurgitating the debunked claims from the widely discredited book ‘Clinton Cash,’” Clinton campaign spokesman Josh Schwerin told FoxNews.com in a statement.

That’s a predictable response anytime a controversy comes up about the Clintons, Blackburn said.

“They always say that something is old news or that it is a right-wing conspiracy,” Blackburn said. “It’s not a right-wing conspiracy. This is about the rule of law and many times the Clintons feel like they can skirt having closer inspection of their activities by claiming that it is a conspiracy.”

The letter detailed how former President Bill Clinton accepted $16.5 million as honorary chancellor at Laureate International Universities, founded by Douglas Becker. The company also gave between $1 million and $5 million to the Clinton Foundation. Bloomberg News reported the U.S. Agency for International Development, an appendage of the State Department, gave more than $55 million to Becker’s International Youth Foundation, while Hillary Clinton was the secretary of state.

A Laureate spokesperson pushed back, telling FoxNews.com, “Allegations of any quid pro quo between Laureate, the International Youth Foundation and the Clintons are completely false. … IYF and Laureate Education are independent organizations. Laureate has never received any funds from IYF.” The spokesperson pointed to PolitiFact and Washington Post Fact Checker articles on the issue, while IYF CEO William Reese stated in an open letter that Becker was the board chairman, but the organization has received State Department funding since 1999.

On another front, Uranium One Chairman Ian Telfer donated a total of $2.35 million to the foundation – and the New York Times reported that former President Clinton once received $500,000 for a speech in Moscow from a company promoting Uranium One stock. As secretary of state, Hillary Clinton was among the U.S. officials that approved the Uranium One sale to Russian investors.

Uranium One did not respond to phone and email inquiries. However, citing a complex timeline, PolitiFact ranked the accusation of a quid pro quo as “mostly false.” The fact checks on both companies relate only to past comments by Donald Trump and not the House Republicans' letter.

The foundation’s website suggests contributors do not receive anything in return aside from the knowledge they are making a difference.

The FBI has stayed mum on the subject, though, even after closing the email investigation with no charges filed. During testimony before the House Oversight and Government Reform Committee, FBI Director James Comey responded, “I’m not going to comment on the existence or nonexistence of other investigations,” when asked if the bureau was investigating the Clinton Foundation.

As for the questions over the 501(c)(3) filing, the tax filing for the organization from December 1997 described the organization as running a presidential library, maintaining archives and doing research.

“No mention is made of conducting activities outside of the United States, which is one of the codes included in the IRS ‘Application for Recognition of Exemption’ in effect at that time,” the letter says. “As a result, the Foundation’s global initiatives appear to be unlawful pursuant to the IRS code.”

FoxNews.com’s Fred Lucas and Judson Berger and Fox News’ Peter Doocy, Tamara Gitt and Mike Emanuel contributed to this report.