Chelsea's audacious bid to sign striker Wayne Rooney from Manchester United has been rejected by the Premier League champions.

The 27-year-old Rooney has been pushing for a move since expressing his frustration to the club about his lack of playing time towards the end of last season.

But both Alex Ferguson and David Moyes, who succeeded his fellow Scot as manager in May, have insisted Rooney is not for sale since he has two years left on his contract.

Despite those public statements, Chelsea has maintained its pursuit of the England striker, culminating in a formal bid submitted to its Premier League rival.

The London club was moved to confirm the bid to deny reports that it had offered midfielder Juan Mata or defender David Luiz as part of a 10 million pound ($15 million) offer.

"Chelsea Football Club can confirm that yesterday it made a written offer to Manchester United for the transfer of Wayne Rooney," Chelsea said in a statement.

"Although the terms of the offer are confidential, for avoidance of doubt ... the proposed purchase price does not include the transfer or loan of any players from Chelsea to Manchester United."

Rooney also sought to leave United in 2010 but backed down after negotiating a new and improved contract with the club.

Back then, despite underperforming at the 2010 World Cup, Rooney was widely considered among the world's top strikers.

Now, he is no longer the No. 1 choice at United, slipping behind striker Robin van Persie at Old Trafford last season and often playing in central midfield.