New York Attorney General Eric Schneiderman has issued a subpoena over the U.S. Chamber of Commerce's finances, just months before this year's U.S. elections, the Chamber said on Wednesday.

The Chamber gave no details about the subpoena, but a person familiar with the situation said Schneiderman was investigating whether a nonprofit affiliate funneled money to the Chamber for use in political activity.

Thomas Collamore, the Chamber's vice president for communications, said the subpoena by Schneiderman, a Democrat, was "curiously timed."

"In the midst of a highly charged political season, it comes as no surprise that the New York State Attorney General would use his office to rehash a very old story about the Chamber's finances," Collamore said in a statement.

In 2010, a group called U.S. Chamber Watch sent a letter to the Internal Revenue Service saying the Starr Foundation, a $1.25 billion foundation chaired by former American International Group Inc head Maurice Greenberg, had given about $19 million to the National Chamber Foundation.

The National Chamber Foundation then loaned $18.1 million to the U.S. Chamber of Commerce, the letter said. There was no indication that any significant part of the loan had been repaid, it said.

Schneiderman's office began the probe after receiving a complaint from a watchdog group last year, the person familiar with the situation said.

The Starr Foundation did not return phone calls seeking comment. A spokeswoman for the law firm Boies Schiller and Flexner, which represents Greenberg in a different matter with the New York Attorney General's office, did not comment on the latest probe.

Jennifer Givner, a spokeswoman for Schneiderman, declined to comment on the investigation, which was first reported by the New York Times on Wednesday.

The U.S. Chamber of Commerce is the world's largest business organization and is the voice in Washington, D.C. for more than three million businesses, according to its website.

The National Chamber Foundation is a nonprofit affiliate group, barred by tax rules from trying to influence legislation as a substantial part of its activities and which may not participate in any campaign activity for or against political candidates.

The probe is being conducted by the charities bureau of the New York Attorney General's office. Under state law, charities that raise money or do business in New York must annually file reports with the attorney general's office and provide an Internal Revenue Service form if they solicit $25,000 or more in contributions.