Updated at 4:43 p.m. Thursday: Revised to clarify that Sen. Chuck Grassley's inquiry into six ministries didn't seek to determine whether the ministries had broken tax rules.

Investigators with the Internal Revenue Service and the U.S. Postal Service served a search warrant Wednesday at the Grapevine offices of televangelist Benny Hinn.

A large number of agents walked in and out of the offices with boxes, KXAS-TV (NBC5) reported, but officials wouldn't confirm to the TV station what they're investigating or whether they're looking into Hinn.

Televangelist Benny Hinn raises his hands in prayer during a service at the Blaisdell Concert Hall in Honolulu in 2002. (Ronen Zilberman/The Associated Press)

A woman who answered the phone for the Benny Hinn Ministries headquarters said she had no information.

Hinn was the subject of a 2007 U.S. Senate inquiry that looked into the spending of six televangelists. Sen. Chuck Grassley, R-Iowa, questioned the personal use of church-owned airplanes, luxury homes and credit cards by pastors and their families.

The review, which ended in 2011, raised issues for Congress to consider but didn't seek to make a determination as to whether the ministries had broken tax rules, said a spokeswoman for Grassley.

Hinn's ministry said at the time that it complied with tax regulations for religious nonprofits. But it told Grassley that it had made changes in how it governs its ministry and sets compensation.

Several media outlets have investigated Hinn, a well-known pastor from Israel who claims that God uses him to miraculously heal people who are sick. He calls it "the anointing."

What we know so far about federal investigation at @Benny_Hinn ministry offices in Grapevine. More on @NBCDFW at 4&6 https://t.co/hyO6h7tyyh — Alice Barr (@AliceBarrNBC5) April 26, 2017

He's been accused of being a con man and criticized for living extravagantly — flying in a private plane and staying in fancy hotels.

"I think if I was fooling the people, over 35 years of it now, I would have been caught already fooling them," he told ABC's Nightline in a 2009 interview.

He told the news program at the time that his salary was more than $500,000, but he wouldn't give an exact figure.