Carlisle, chairman of the PFA, revealed he has already had several meetings with Reading striker Roberts, who, along with Ferdinand, refused to wear a Kick It Out T-shirt last weekend. However, the nature of the proposals surrounding the potential breakaway group, which could sever links with the PFA, are still unknown by the union.
"I've had a number of conversations with Jason over the past few months. The most recent of them was on Sunday and they will continue," Clarke said. "Jason explained one or two things to me but I don't know what the full intentions or the requests are of this breakaway group."
He added: "Until we get everyone in and fully ascertain what they want and the direction they want to go in I can't really comment much further. The threat is very real because the proposal is there and the discussions have been had so it's obviously something that has been mooted within the industry.
"We have been having meetings with Jason and we have desperately been trying to get Rio into the meetings and that will continue.
"We will have those discussions with them at the time. We need to know exactly what it is they are wanting. Whether this is a movement that is in full flow and whether they think it is going to happen irrespectively, or whether it is something where they are trying to instigate change within the organisations that are currently in place.
"These are things that we have to hear, assess and weigh up."
Clarke is concerned the potential formation of a separate players' union could derail current efforts to drive racism out of football.
Manchester United defender Ferdinand was one of the players who did not wear a Kick it Out campaign T-shirt in the warm-up to United's match against Stoke City at Old Trafford at the weekend. Carlisle backed Ferdinand's right to free speech after his protest but is cautious about the benefits a breakaway group would bring in the fight against racism.
"It has the potential to be divisive as when you establish a black players union it would instantly define 'us and them' and that's something we really need to work against," Carlisle said. "We don't need to separate the players when the whole focus and goal of anti-racism is to campaign for unity so that is something we will be talking about, definitely."
Meanwhile, Arsenal manager Arsene Wenger feels it would be "bad" to split football's battle against racism with the formation of a breakaway black players' union.
Wales and Aberdeen keeper Jason Brown claimed black players might reluctantly be driven towards setting up a breakaway anti-racism group because they feel not enough is being done.
But the Arsenal manager said: "I think any split is bad. If there is no racism, if you want to fight against racism, you should not create any federation on a difference that you want to fight against. I personally can't see the logic in that."
UEFA are promoting anti-racism projects along with Football Against Racism in Europe (FARE) at this week's Champions League and Europa League games.
The issue continues to make headlines in the wake of John Terry's domestic ban by the Football Association for using racist language towards QPR defender Anton Ferdinand and abuse suffered by England under-21 players during a recent international in Serbia.
Wenger is fully behind the initiatives and said: "I feel it is important to happen at any moment.
"Racism or xenophobia or any other differences that can exist between people, for example different cultures - you have to always show respect for everybody and every culture and every human being, no matter where you come from and no matter when it is in the season.
"That is why I feel that what happened during the weekend is very sad."
Arsenal midfielder Aaron Ramsey maintains players are all behind the campaigns.
The Wales international said: "We should all try to get together and try to get [racism] out of the game. It is not a good thing that has happened lately, but it is not really for me to comment on. Nobody likes to see that, and personally I don't like to see that in the game. We all support that here."