Giuliani's Lawyer Robert Costello told the Journal that the warrant outlined an investigation into the suspected violation of overseas lobbying regulations.

Costello also called the raids "legal thuggery," saying he'd repeatedly offered in vain to answer questions from investigators if they agreed to detail the subject of their probe.

"It's like I'm talking to a wall," he told the Journal.

Investigators in the Justice Department had tried for months to secure the search warrant, according to the Times.