The National Rifle Association accepts foreign contributions, it told the ranking Democrat on the Senate Finance Committee in a recent letter, but the gun rights group insists none of it goes towards elections and is all raised and spent "within the bounds of the law."

The NRA is under pressure after the Parkland shooting and its response to it. A recent McClatchy report also claimed the FBI had looked into whether a Russian banker funneled funds to the NRA to help Donald Trump's campaign.

The NRA acknowledged that it allows for the transfer of funds in between its various entities, making it difficult to track its funding entirely. Senate Finance Committee ranking member Ron Wyden, D-Oregon, had asked the NRA a series of questions about how and where it raises donations. NPR first highlighted the NRA's claim regarding foreign funding.

Get Breaking News Delivered to Your Inbox

"No funds from foreign persons are accepted for the NRA Political Victory Fund (NRA-PVF), a political action committee that reports all of its expenditures to the FEC (Federal Election Committee)," a March 19 letter from NRA General Counsel John Frazer to Wyden states. "Accounts that report no expenditures to the FEC, or that report only some expenditures to the FEC, receive funds from foreign persons only for purposes not connected to elections, as permitted by federal law."

"You also ask whether the NRA makes transfers between the various types of accounts," Frazer added. "Transfers between accounts are made as permitted by law."

IRS records reviewed by CBS News show that the NRA answered "yes" to the question, "Did the organization have aggregate revenues or expenses of more than $10,000 from grant-making, fundraising, business, investment, and program service activities outside the U.S., or aggregate foreign investments valued at $100,000 or more?" on its 2016 forms.

Frazer repeatedly insisted that the NRA is in compliance with all election law requirements, and that staff members who handle major donations have "ongoing compliance training, in which they are taught that funds may not be accepted from foreign persons in connection with U.S. elections. Large, unexpected contributions from any individual or entity are obviously of great interest to fundraising staff and will prompt further research about the donor."

The NRA also answered questions about a 2015 Moscow visit taken by several NRA associates, and any fundraising actions involving Russians. Frazer defended the visit, claiming that a NRA member on the trip, Joe Gregory, has only honorary titles within the organization, and travelled to Russia in his "personal capacity." The NRA general counsel also claimed no Russian nationals were ever members of NRA's Golden Ring of Freedom, a designation reserved for top donors.

Wyden, however, did not find all those answers satisfactory. He fired off a letter to Frazer on Tuesday in response.

"I appreciate your assertion that the NRA complies with applicable federal elections laws; however, it is incumbent on lawmakers to not only investigate compliance with the law, but also to ascertain whether present law provides sufficient safeguards to protect the American political process from foreign influence," Wyden wrote.

"That is why I asked specifically whether your organizations make electioneering, issue advocacy, educational voter mobilization, or communications expenditures (including expenditures not subject to FEC disclosure requirements) out of such accounts.

In your recent letter, you chose not to fully answer this question with respect to expenditures not subject to FEC disclosure requirements. These questions have become all the more pertinent in light of recent reports suggesting the NRA significantly increased online advertisement spending to sway American political discourse following the mass shooting at Marjory Stoneman Douglas High School in Parkland Florida."

In his letter, Wyden demanded further information on foreign NRA funding that has occurred over the last three years. Wyden also asked if any Russian national had ever been a member of any NRA donor program.