Former England manager McClaren, 50, signed a three-year contract on Monday and will attempt to end the club's 13-year exile from the Barclays Premier League. Forest's former boss Billy Davies, sacked on Sunday following two successive npower Championship play-off semi-final defeats, often cited lack of funding as the main reason why the east Midlanders have become the 'nearly men' in recent seasons, but Arthur insisted funding had always been available.
Arthur said: "We have a very good squad, but he will be looking to improve it in certain positions. I think we all know that the first position we must try and sort out is left-back."
He added: "Money has been available in the past. (Chairman) Nigel Doughty has put £25million into the club in the last two seasons, so I think it's a bit of a fallacy to suggest that no money has been made available.
"Steve will have similar funds available to him if he can identify a player of the quality who will enhance the quality of the current squad.
"We have a very good squad, but he will be looking to improve it in certain positions. I think we all know that the first position we must try and sort out is left-back."
McClaren, sacked in disgrace by England in 2008 and recently linked with the vacancy at Aston Villa, returns to club management in this country after reviving his career in Holland and then spending an ill-fated spell in Germany with Bundesliga side Wolfsburg.
Forest, relegated from the top flight in 1999, have been unable to claw their way back and languished for three seasons in League One from 2005 to 2008, but Arthur pointed to McClaren's track record in club management as the reason for his appointment.
Arthur said: "Steve has a proven track record of coaching and managing at club level, having played a key role in helping Manchester United secure the Champions League trophy [in 1999], three Premier League titles and an FA Cup; guided Middlesbrough to the League Cup and also to the final of the UEFA Cup and led FC Twente to their first ever Dutch title."
Source: PA
Source: PA