David Gill has sent a "hands off Ruud" warnings to both Real Madrid and Barcelona.

Gill revealed he had taken the unprecedented step of writing to the Spanish giants to tell them star striker Ruud van Nistelrooy will not be sold despite renewed speculation linking him with a move away from Old Trafford.

The United hierarchy are growing increasingly frustrated at talk that van Nistelrooy may quit at the end of the season, even though he only signed a five-year contract in January and has repeatedly insisted he is going nowhere.

And, while Gill understands his letters may not quell the speculation completely, he is hopeful they will be enough to ward off the unwelcome interest in United's star striker.

"I have written to the clubs concerned and told them Ruud is not for sale," Gill told MUTV.

"We want to make it very clear to them what the position is and make sure the message gets through.

"We can't be any more specific. We've been categorical about this. The facts of the situation are the same as they were a week, two weeks, three weeks, four weeks ago.

"We've signed Ruud on a long contract and that wasn't done lightly or without planning. He has another four and a half years here. That is fact. There is no point saying anything else.

"Ruud outlined the situation in Saturday's match programme. I have spoken to him today and we all agree it is in everyone's best interests that this speculation stops."

In an interview with the United official programme ahead of last weekend's 1-0 defeat to Liverpool, van Nistelrooy made it quite plain that he was not interested in leaving a club for whom he has scored and amazing 106 times in less than three seasons since his £18.5 million move from PSV Eindhoven.

"What can I do," he said. "I signed a contract here showing that I don't want to leave but still people write stories.

"It doesn't matter what people say. I am staying here, I am not going anywhere and I'm optimistic about the future."

Ironically, it was the 27-year-old's failure to play against Liverpool which raised doubts over his position at United.

It was reported the former PSV Eindhoven star, who has not scored in the league since February 11th, had exchanged angry words with Bellion last Friday.

And, while the thigh strain cited by Ferguson as the reason for his forward's absence on Saturday was enough to keep him out of Holland's friendly win over Greece last night, it was his failure to watch the Liverpool game from the Old Trafford stands which attracted most attention.

United officials have reacted to suggestions of any bust-up with Bellion with astonishment, while the player's agent Rodger Linse has attempted to distance himself from the allegations that he has held talks with Real.

However, mindful of United's repeated insistence 12 months ago that David Beckham would not be leaving for the Bernabeu, fans remain wary about the prospect of losing such a popular player who looks capable of forging a devastating partnership with new arrival Louis Saha.

In just six games together, the pair have already netted nine times and van Nistelrooy has already spoken in glowing terms about his relationship with the new France international.

"It is good to have a strike partner like Louis," said van Nistelrooy.

"He has shown what he is capable of already and there is definitely a good connection between us.

"We haven't had many games together but the results have been quite promising and in training it looks good as well, so hopefully next season you will see the best of us."