Charles Green has tried to defend his occasional use of the word "P***" when addressing his friend and colleague Imran Ahmad by saying it was "lighthearted".

The Rangers chief executive was responding to criticism from Show Racism the Red Card, the anti-racism charity, who said his comments were "ill-advised" and that the term is "highly offensive".

Green made the remark during a newspaper interview at the weekend, saying that he sometimes refers to Ahmad, the Rangers commercial director, as his "little P*** friend", while Ahmad calls him a "Yorkshire so-and-so". Green defended himself by stressing that the language is not used in a disparaging way, although he later admitted in an interview with STV that he would discipline any Rangers player who used the term.

"The point I made when I was being interviewed the other day was about my relationship with Imran," Green told STV yesterday. "It's not normal language for me. I only use it with Imran. I don't use it in the public domain. Would I accept it from a player? In terms of being said in a friendly way or a disparaging way? No, it would be inappropriate. He would subject to an investigation or if there was a complaint. Imran hasn't complained."

Green's use of the term was condemned by Show Racism the Red Card, who said somebody in his position should not have used such "racist and offensive language".

"The use of the term 'P***' is highly offensive and it is something that we are trying to educate young people against," the charity said. "For the CEO of Rangers to use the term in any context is not helpful as it sends out the wrong message. Show Racism the Red Card has a long standing working relationship with Rangers FC. The club is an excellent supporter of our anti-racism and anti- sectarianism campaigns."

In his interview with STV, Green admitted he might have been wrong to describe this as the worst-ever Rangers team, admitted that the board and the shareholders could oust him at the annual general meeting in August if they do not like the way that he is running the club, and defended the club's sacking of Fran Sandaza after the striker admitted to a prank caller that he would consider a move away from Ibrox.

"If Lionel Messi was a Rangers player and he was recorded saying, 'I don't want to play for Rangers, get me a contract, I'll go and sign for another club, give it to me don't go through the club,' I'd sack Lionel Messi," Green said. "If anyone denigrates this club, or has no respect for the badge, if anyone doesn't want to work here, then go. We are going to make sure this club is not being reported for the wrong reasons."