Manchester United have rejected a second offer from rivals Chelsea for unsettled forward Wayne Rooney, the Premier League champions said on Monday.
Chelsea tabled an improved bid for Rooney, having had an initial cash offer rebuffed last month.
"A bid was received yesterday and immediately rejected," a United spokesperson told the BBC.
"Our position remains that he is not for sale."
New Chelsea boss Jose Mourinho has made the 27-year-old his top transfer target, but United have had trouble signing other players this summer and have been frustrated by their pursuit of Barcelona's Cesc Fabregas.
England striker Rooney has been reported to be 'angry and confused' with his situation at United.
He was upset at comments by new manager David Moyes that suggested he was a backup to Premier League top scorer Robin van Persie, and has been the subject of transfer speculation since retired manager Alex Ferguson said at the end of last season that the striker had asked to leave the club.
Rooney joined United for $41.24 million in August 2004 and has made 402 appearances for the club, scoring 197 goals and winning five league titles and the Champions League.
He has two years left of a contract that earns him a basic salary of some $381,800 a week. Rooney left the club's recent pre-season tour of the Far East with a hamstring injury, hours after arriving in Bangkok.
The second bid and United's swift response could prompt Rooney to hand in an official transfer request.