Ali Carter said he feels sorry for Ronnie O’Sullivan and does not think the world number one is “that well mentally” as the pair’s bitter war of words continued.

O’Sullivan described Carter as “a f****** nightmare” and said he needs to “see a counsellor” after beating his fierce rival in Sunday’s Masters final.

The 48-year-old was hitting back at Carter, who claimed the seven-time world champion had “snotted on the floor” during their match at Alexandra Palace, which O’Sullivan won 10-7.

The World Snooker Tour said on Tuesday morning that O’Sullivan’s outburst was “under review”, with Carter then going on the offensive later in the day.

The pair are both playing at the Grand Prix in Leicester this week and, speaking to ITV4 ahead of his match with Yize Wu, Carter said: “Ronnie is entitled to his opinion. I just said what it is and how it was and I talk facts. It is as simple as that.”

Asked whether he was angry at O’Sullivan’s comments, he said: “Angry about what? It makes no difference to me what he says. He says different things on different days. I don’t think he even knows what is going to come out of his mouth at certain times.

“I actually feel a bit sorry for him. I don’t think he is that well, mentally. So we move forward and we go again this week.”

O’Sullivan is not due to play until the evening session, so it is unlikely the pair will cross paths at the Morningside Arena and they cannot meet until the final.

O’Sullivan caused a stir when told several newspapers: “He needs to sort his f*****g life out. I’m not going to skirt around it any more, tip-toeing on eggshells around someone like that. He’s a f*****g nightmare.

“Playing snooker against someone like that is a nightmare. He’s not a nice person. It’s not a nice vibe he leaves around the table.

“I’ve said my piece, I don’t give a s**t. I’ve said it now, done. You know what he’s like, everybody knows what he’s like.

“He’s got issues. F*****g why has he got issues with me? I’m not having it.”

O’Sullivan added: “He’s got beef with me. He’s got issues, he’s got to sort his life out, he’s got to see a counsellor or something. He’s got to sort it out because I haven’t spoken to him for 20 years.”

The pair’s long-running heated rivalry boiled over during their 2018 World Championship match at the Crucible when O’Sullivan barged into Carter at the table.

At Alexandra Palace on Sunday, Carter had a heated exchange with someone in the crowd, who had called out when he was about to take a shot.

Carter, 44, said: “There were a couple of things that happened out there that go unnoticed. Well, they don’t go unnoticed – anyone with an eyesight or a brain can see what’s going on.

“It’s disgusting, quite frankly. No-one wants to say anything, do they? (O’Sullivan) snotting all over the floor and all that.

“I mean it’s outrageous behaviour from a top professional. If it gets swept under the carpet then for me, it’s not good.”

O’Sullivan is currently involved in a disciplinary dispute with the game’s governing body, the World Professional Billiards and Snooker Association, over comments he made about unsanctioned exhibition matches.

It is expected the Carter matter will be referred to the WPBSA.