In a new autobiography, which has been serialised by English newspaper the Sunday Times, Campbell claimed the FA were uncomfortable making him captain because he is black.
The FA declined to comment on the claims made by the former defender, who made 73 appearances for his country, three as captain.
However, Powar, the chief executive of the Football Against Racism in Europe (FARE) network, has pointed to a lack of diversity within the governing body.
Speaking to Perform, Powar said: "The FA is not a very diverse organisation; it's difficult to find ethnic minorities in leadership positions and, therefore, the suspicion arises that somebody like Sol Campbell, with his achievements, his potential, is not recognised in the same way as a white player.
"That's an argument that has been made by a number of people over a number of years, and unfortunately the FA remain the same as they always have been in their make-up.
"As a direct quote he (Campbell) said we need more black and Indians in the leadership of the FA.
"Now if that was the case, and the FA could point to those individuals, I think the point (made by Campbell regarding being overlooked for the captaincy) would be easily dismissed.
"But it's not the case, and I think there will be many more arguments in the future until the FA becomes more diverse.
"I think it will add to the pressure that's been there for a while. We see reports on the make-up of the FA and it is hideously white, it is hideously male."
