The Senate Ethics Committee is reviewing whether Sen. Robert Menendez, D-N.J., inappropriately accepted gifts from a political donor who is under investigation by federal investigators.

"We are aware of the news reports regarding the FBI raid on Dr. Melgen's office," Sen. Johnny Isakson, R-Ga., the top Republican on the ethics committee, said to CBS News in a statement. "The Ethics Committee will follow its established procedures in this matter."

Late Tuesday night, the FBI and the Health and Human Services Department raided the West Palm Beach, Fla., offices belonging to Dr. Salomon Melgen, an eye doctor who has made large donations to Menendez, the New Jersey State Democratic Committee and other politicians. The FBI has not said why it was raiding Melgen's office Tuesday night, but according to the Miami Herald, records show that Melgen has an outstanding IRS lien of $11.1 million for taxes owed from 2006 to 2009.

Read more at CBS News