The U.S. Treasury on Friday issued a formal response to a Republican lawmaker who has been requesting financial "suspicious activity reports" on President Joe Biden's son Hunter, saying that it would consider only official requests from relevant congressional committees.

Democrats control Congress and its committees, making such a request from Republicans virtually impossible, though mid-term congressional elections could shift control. The request to Treasury referenced the Bank Secrecy Act which is intended to help prevent money laundering.

Representative James Comer of Kentucky, the top Republican on the House Oversight and Reform Committee, has accused the Treasury of changing rules to shield Hunter Biden's business dealings with foreign companies.

Former President Donald Trump and his Republican allies in Congress made Hunter Biden's business dealings in China and Ukraine a line of attack against the elder Biden during the 2020 election campaign. Hunter Biden has denied any wrongdoing.

In July, Comer said that Treasury officials told the committee's Republican staff that the department would not provide access to the suspicious activity reports unless Democrats join the request.

Suspicious activity reports are filed by financial institutions when clients make large cash transactions or transfers above $5,000 that could signal money laundering or other offenses, although many such transactions are legitimate.

In a letter to Comer seen by Reuters, the Treasury said such reports are normally kept confidential, but that it complies with current statutes and regulations on providing requested information to Congress. Such access would require written requests from committees, but Treasury Secretary Janet Yellen has the final say.

The House Oversight Committee is controlled by Democrats.

"Under the current regulation, the Secretary may make BSA information available to 'Congress, or any committee or

subcommittee thereof, upon a written request stating the particular information desired, the criminal, tax or regulatory purpose for which the information is sought, and the official need for the information,'" the Treasury wrote. "These decisions are entrusted to the Secretary's discretion."

Treasury said a requesting committee should provide a detailed statement of purpose for seeking the information to ensure that it meets Bank Secrecy Act purposes and protecting law enforcement investigations.

The requirement for a committee request would effectively shut down Comer's demands for reports involving Hunter Biden because Democrats now control the House of Representatives and its committees. They have refused to aid Republicans seeking to dig up information that would be potentially damaging to the president and Democratic candidates.

But the tide could shift if Republicans win House control in November, enabling the House Oversight Committee leaders to make a formal request for suspicious activity reports involving Hunter Biden, a move that could lay the groundwork for a probe into his finances.

The Treasury said that when it approves requests for Bank Secrecy Act information to any authorized party, it is provided only in secure reading rooms that are meant to keep the information confidential.