Manchester United boss Sir Alex Ferguson insists he doesn't need to buy in January.

Some sections of the press and, indeed, the Old Trafford faithful have implored Sir Alex to strengthen during January, calls that grew in volume following United's recent exits from both the Carling Cup and Champions League competitions.

"All things being equal, I am perfectly happy with the strength of our squad in terms of depth, quality and age range," Sir Alex writes in his Boxing Day notes in matchday programme United Review.

"I will not be swayed by the endless tweets and blogs urging the club to get busy in the transfer market next month.

"As far as I am concerned I am marching perfectly in step, true to my beliefs and principles. While recruiting some of the world's leading players can lift you into contention for honours, it doesn't necessarily take you all the way, as I hope we will be able to demonstrate before the end of the season as other factors come into play.

"You can never say never in football, of course, because fortunes can fluctuate wildly - that's the football world. If a really top-class player became available, then we would go for him, or if we picked up any further serious injuries, it might be important to add to our squad.

"But let me reiterate, contrary to what some people seem to be fixated about, money for a transfer is not a problem if I deem it necessary."