Senior detective April Casburn offered information on the phone hacking inquiry in exchange for cash to the News of the World, a court has heard.
Det Chief Insp Casburn of the national terrorism financial investigation unit allegedly rang the NotW's newsdesk in September 2010 with names of its former journalists who were under investigation.
She demanded money and gave the names of two people during the conversation to journalist Tim Wood, the court was told.
"She did not give her name but introduced herself as a senior policewoman and proceeded to give me the information," Wood told the jury.
Casburn allegedly phoned the News of the World because she was angered by Lord Prescott's "interference" in the phone hacking scandal.
Wood reported that Casburn told him there were six members of staff under investigation, including ex-editor Andy Coulson and former reporter Sean Hoare.
The officer, 53, from Hatfield Peverel in Essex, is also facing a separate charge under the Official Secrets Act for holding secret documents at home without permission.
Prosecuting, Mark Bryant-Heron said Casburn "sought to undermine a highly sensitive and high-profile investigation".
"The prosecution says that the act of telephoning the News of the World to offer to sell information was misconduct in public office," he said. "It was a gross breach of the trust that the public places in a police officer not to disclose information on a current investigation in an unauthorised way, or to offer to do so in the future for payment."
Casburn did not deny calling the newspaper but said she did not ask for money.
She said she made the call because she was concerned that police resources that were supposed to be used to fight terrorism were being assigned to the phone hacking inquiry.