Manchester United reportedly offering big money to lure Germany star Toni Kroos to Old Trafford

REPORTED interest from Manchester United has Bayern Munich worried over the future of star midfielder Toni Kroos.

FRANZ Beckenbauer has warned Germany's Toni Kroos to tread carefully with Bayern Munich after revelations that the midfielder's contract extension talks have ground to a halt amid reports Manchester United want him.

“He shouldn't raise the stakes too high,” said Bayern's honorary president Beckenbauer, who managed and captained West Germany to World Cup titles.

Manchester United reportedly keen to spend big on Toni Kroos.

“Bayern will make an effort to keep him but, when the demands are too high, a decision will be made.

“There is no player who you have to give everything to keep. Everyone is replaceable.”

Kroos has a Bayern contract until June 2015, but the German star has failed to agree on a new deal with the runaway Bundesliga leaders and wants to become one of the club's top earners.

British media reported over the weekend that David Moyes' sManchester United are prepared to offer him $A465,000 per week.

Kroos is said to want to triple his salary with Bayern to $A18.5 million to become one of the European champions' best-paid stars.

Bayern's director of sport Matthias Sammer has said the Bavarians are keen to keep the attacking midfielder.

“We know that he is a very good player and we want to continue with Kroos,” said Sammer.

“Everyone at the club sees it that way.”