Manchester United on Saturday said on its website that audio tapes apparently recorded at Old Trafford locker room on 6 November were offered to The Sun newspaper. The Sun gave
United the tapes on Friday.
United beat Chelsea 1-0, ending the Blues' 40-match unbeaten Premier League streak.
According to the tabloid newspaper the tapes include pre-match and halftime talks, and post-game celebrations.
The team's veteran manager Alex Ferguson, is reported to offer playing tips to stars Wayne Rooney and Ruud van Nistelrooy.
After the victory defender Rio Ferdinand is heard saying the victory will silence critics of the club.
The Sun says an eavesdropper smuggled a radio transmitter into the dressing room and then tuned into the frequency from a position nearby, recording over two hours of conversation.
"We are grateful to The Sun for bringing this breach of security and privacy to our attention," United director of communications Phil Townsend said.
"We have launched our own investigation and, if necessary, will involve the police."