Farhad Moshiri is a London-based investor with close links to billionaire Russian oligarch Usmanov, who owns around a 25% stake in the club.

Moshiri is "mystified" as to why the Gunners board rejected a rights issue proposed and underwritten by Usmanov this summer which he intended to generate transfer cash for manager Arsene Wenger and also reduce the club's long-term debt.

Rather than spending, the summer has mainly been about the players leaving the Emirates Stadium and Moshiri insisted the sale of Togo striker Adebayor was a "worrying" development.

"There is no question that it is a talented squad but there have been very limited additions and you cannot help but feel that there is still not enough depth to that squad," he said.

"To compete on a number of fronts over a long season, especially with the African Cup of Nations when we are going to lose Kolo Toure as well, that is going to make it very difficult."

Asked whether the club were in danger of slipping out of the top four, he told BBC Radio Five Live's Sportsweek programme: "I think there are certain risks but I have confidence in Arsene to keep us within the top four, but you cannot ignore the risk."

On the subject of Adebayor's transfer, he added: "He did not have the best of seasons last year so I can understand the fans' feelings, but the bottom line is we are down a proven striker going into the next season.

"He averaged 20 goals a season so unless we replace him with a striker of that talent we will be weaker going forward.

"That is the most worrying thing because Manchester City with their enormous firepower are one of the challengers for the fourth spot and I would have felt much better if he had been sold to any other club than Man City."

Moshiri does not expect there to be much more transfer activity at Arsenal this summer.

"Based on our analysis any money is very limited and possibly spent already and I don't think there are any spare funds with the exception of Adebayor's proceeds," he said.

"Arsenal are the only club in the land that rejects an offer to pay their huge debts in these troubled times, I'm truly mystified.

"It wasn't just about today, it was about making sure the club was well placed to compete at the highest level of European football for the future."

Moshiri hailed the genius of Wenger but argued that the club had never adequately replaced former vice-chairman David Dein, who worked closely with Wenger on transfers and sold his stake in the club to Usmanov almost two years ago.

"Based on what the fans say, I think the short answer is that (Dein) was never replaced," Moshiri said.

"What I'm sure of is that Arsenal enjoyed great success under the Wenger-Dein axis and that has never been repeated."