Former News of the World managing editor Stuart Kuttner told police that he had confirmed with friends of murdered schoolgirl Milly Dowler that the paper had her correct mobile number.
The court also heard that News of the World journalists listened to Milly Dowler's voicemail messages while she was still believed to be missing.
Kuttner called Surrey Police in April 2002 to inform them of a voicemail left on the missing girl's phone by a recruitment agency in Telford, the jury in the phone hacking trial was told.
The Old Bailey heard how Kuttner encouraged police to follow the lead.
He said that the newspapers had "information that may assist the inquiry into the disappearance of Milly Dowler", who was later found murdered.
Kuttner has denied the charge of conspiracy to hack phones. He is one of eight defendants, including Rebekah Brooks and Andy Coulson, who are standing trial on charges related to the News of the World phone hacking claims.
The 73-year-old, who was managing editor at News of the World for 22 years, was unable to attend court on because of ill health.
It was while Kuttner informed officers of the recruitment agency's call that he said that the newspaper had obtained access to Milly Dowler's mobile phone number and pin, the court heard.
In his statement, read in court by DS Kevin McEntee, Kuttner told him: "The News of the World are in possession of a recording of that message" and that the newspaper "had confirmed with schoolfriends" that they had the schoolgirl's correct mobile phone number.
Police told Kuttner that the voicemail was believed to have been left by a "professional hoaxer", a claim that was repeated in the tabloid the following day.
The jury heard that the News of the World's chief reporter Neville Thurlbeck had later called police to inform them that the newspaper "had access" to Milly's voicemail and had acquired the mobile phone number from "sources".
Thurlbeck told police on 13 April that the paper planned to run the story the next day.
The court heard that the publication's former editor Brooks was away in Dubai on that day but she had contacted her colleagues, including her deputy at the time, Coulson.
Coulson, 45, and Brooks, 45, both deny conspiring with others to hack phones. Coulson also denies conspiring to commit misconduct in public office.
Prosecutors said the 2002 story surrounding the voicemail was changed between the first and second editions of the newspaper to remove any mention of a message on her voicemail.
In the first edition, the story on the voicemail quoted the message sent by the recruitment company which, it claimed, said: "We're ringing because we've got some interviews starting, can you call me back? Thank you, bye bye."
When the second edition was printed, the text of the message seen in the first edition had been edited out. The third edition then centred on the "outrage" that the voicemail may have been a hoax, the jury of nine men and three women at the Old Bailey heard.
Ex-Surrey Police press chief Sarah McGregor told the court about the relationship between the News of the World and Surrey Police during the Milly Dowler investigation.
She claimed that the newspaper admitted to hacking the schoolgirl's phone and offered police details of her voicemail.
Cross-examined by Jonathan Laidlaw, QC, the counsel for Brooks, McGregor said that no police officer suggested the News of the World should be investigated for hacking Milly's phone.
According to McGregor, relations between the newspaper and Surrey Police began to deteriorate when the Sun obtained an exclusive, despite being the Sunday paper's "stablemate".
One journalist shouted down the phone: "You [the police] have killed us stone dead in the water" before hanging up.
Coulson, Brooks and the other six defendants deny all charges against them. The trial is expected to last until Easter.