The 21-year-old has been immediately loaned back to Molde where he will remain until January.

The transfer may surprise some after manager Sir Alex Ferguson stressed, just last week that he would not be making any more signings this summer following the arrivals of Michael Owen, Antonio Valencia and Gabriel Obertan.

However the Red Devils manager admitted that after other clubs lodged bids for the Senegalese youngster the Barclays Premier League champions had to act fast.

"We signed a young player yesterday from Norway who we've been looking at for two years," he told the club's official website.

"We weren't intending on signing anyone else after last week - we feel we have a full squad - but the situation accelerated to a point where other clubs started to make bids.

"So we had to decide whether we acted or didn't. We decided to act and he'll be the last person we sign."

even better

Diouf has reportedly interested the likes of Arsenal, Tottenham Hotspur, Ajax and PSV Eindhoven.

Attention in the youngster developed last weekend when Diouf netted a hat-trick in the first nine minutes of a Norwegian league match against Brann before he added another in a 5-2 win.

The new United arrival has scored 30 league goals from 62 matches since signing for Molde, the same club United signed Ole Gunnar Solskjaer from, in 2007.

Molde manager Kjell Jonevret is confident Diouf has the potential to succeed at the Theatre of Dreams and was delighted that the player would stay for the remainder of the Norwegian season.

"This is fun for all of us in Molde, fun for Mame and not least for his family in Senegal," he said.

"That he will stay with us for the rest of the season is really important to us.

"Mame is an interesting player that I have worked with for two years. I don't know what plans United have for him, but he has a great potential.

"Mame is good now, but he can be even better."

www.manutd.com