Saudi Arabia's government donated $1 million to a nonprofit that has ties to Sen. John McCain, according to federal tax filings obtained by ABC15.

As first reported by Bloomberg on Thursday, the Royal Embassy of Saudi Arabia donated $1 million to the McCain Institute Foundation in the 2014 tax year.

The institute foundation supports the McCain Institute for International Leadership at Arizona State University, a partnership that started in May 2012. The institute describes itself as a "non-partisan do-tank," according to its website.

Debbie Williams, a spokeswoman for the ASU Foundation, told ABC15 that the donation was a "general, unrestricted contribution." The ASU foundation supports the institute.

"The ASU Foundation has received several million dollars in donations over the past five years from a wide variety of foundations, businesses, philanthropists and other sources to support the work of the McCain Institute," Williams said.

The institute's website lists a multitude of donations of at least $100,000, including Wal-Mart Stores, Inc. and Chevron.

Although the senior senator participates in some of the institute's activities, McCain spokeswoman Rachael Dean denied any formal involvement in a statement to ABC15.

"Senator McCain was greatly honored that Arizona State University established an Institute for International Leadership named for him and his family, in recognition of their generations of service to the country in international affairs," Dean said. "Senator McCain holds no position with the McCain Institute for International Leadership at Arizona State University, or with its supporting organizations, and has no role in the governance or operation of the Institute."

Foreign campaign contributions to political candidates are prohibited, according to the Federal Election Commission.

McCain is seeking his sixth term in the U.S. Senate this November. His challengers include Republican Kelli Ward and Democrat Ann Kirkpatrick.