Manchester United manager Sir Alex Ferguson insists that the club are not prepared to sell want-away striker Ruud van Nistelrooy on teh cheap.

United are believed to be demanding at least £15m for the 30-year-old, while Real Madrid have made an improved offer of £10.3m and Bayern Munich are also keen on signing the Dutch striker.

“We know our value. If we are going to sell Ruud we should get the proper value,” Ferguson told MUTV.

“He is one of the best strikers in the country, one of the best strikers in Europe, so when you think about Andriy Shevchenko going for £35m – he is a similar age group.”

Ukraine captain Shevchenko, 29, joined United’s Premiership rivals Chelsea in May.

Real’s new offer remains short of United’s valuation and Ferguson says that they and Bayern need to up their bid significantly if they wish to sign van Nistelrooy.

“I read it on teletext and I spoke to chief executive David Gill and nothing has really materially changed,” said Ferguson.

“They have slightly increased it but it is nothing really. An increase of about two bob or something.

“We know the value of the player so at the moment he is a Manchester United player.”

Asked if both Real and Bayern were a long way short of United’s valuation, Ferguson stated: “Absolutely.”