The Globe newspaper said it confirmed through a Freedom of Information Act request that Taylor was an asset of U.S. intelligence agencies, including the CIA.
The newspaper found that Taylor served as a source of information on intelligence related to former Libyan leader Moammar Gadhafi, allegedly killed by rebel forces during the war there last year.
He may have served in an additional capacity by providing sensitive information related to the Soviet Union and wide-ranging African issues.
Douglas Farah, a senior fellow at the International Assessment and Strategy Center, told the Globe intelligence officers "may have stuck with him longer than they should have but maybe he was providing something useful."
A spokesman for the International Criminal Court in The Hague, Soloman Moriba, told the newspaper the close ties to Washington may explain why the U.S. government was reluctant to use its influence to bring Taylor to justice before he resigned in 2003.
Moriba added that the court could reach a verdict on Taylor early this year.
Taylor is facing war crimes charges at an international court for allegedly funding conflict in Sierra Leone with so-called blood diamonds. He attended Bentley University in Massachusetts.