U.S. authorities investigating an alleged effort by associates of Rudy Giuliani to funnel foreign money into U.S. election campaigns have collected records of financial transactions for more than 50 bank accounts as well as correspondence on 10 email addresses, a federal prosecutor said in a New York courtroom.

The disclosure suggests an investigation potentially encompassing a vast array of people and money beyond what has been publicly disclosed since charges were first filed against four defendants last week, including two men close to Giuliani who were arrested by the FBI as they tried to leave the country with one-way plane tickets. The probe has been active for at least several months, before U.S. Attorney General William Barr assumed office, Bloomberg reported last week.