Wade is a three-time world championship semi-finalist

James Wade has apologised for his behaviour during and after his victory against Seigo Asada at the PDC Darts World Championships, saying he was "fighting a battle" with himself.

Wade, who won 3-2 in the second round, celebrated in his Japanese opponent's face after clinching the second set.

After Wednesday's win, Wade, said he "wanted to hurt him in his face".

On Thursday, Wade explained he had a "hypomania episode" before the game but how "upset" he was with his actions.

"I hope people can understand how remorseful I am," the 35-year-old Englishman added.

Former player and Sky Sports pundit Wayne Mardle described ninth seed Wade's performance as "aggressive" and likened it to "bullying".

"I dug in deep there. It's a magnificent feeling. I could have easily lost that. I've done it for my son, for my country, so it's good," Wade told Sky Sports following the win on Wednesday.

"I kept giving it to him, I wanted to hurt him, I wanted to really hurt him in his face and I wanted to progress. That was for my 10-week old son and for the UK."

In a statement on Twitter on Thursday, Wade - who hails from Aldershot - said: "I would like to take this opportunity to sincerely apologise for my actions last night.

"Seigo Asada is a great player and I would like to say sorry to him, the fans and the PDC. Anyone that has followed my professional career will know this was very out of character for me and I'm disappointed in myself with the way I acted both on the stage and in my interviews after the match.

"I was fighting a battle with myself before I even got on the stage due to a hypomania episode which can happen to me at any time and no-one is more upset than I am about what happened."

Wade was beaten in the first round last year by Keegan Brown and could face his fellow Englishman again in round three this time. Brown must first play 2006 champion Jelle Klaasen of the Netherlands in round two.

'Out of character' - darts chief Hearn

Wade will be referred to the Darts Regulation Authority over the incident, although there is sympathy from the PDC for his condition.

PDC chairman Barry Hearn told BBC Sport: "It will be up to the independent panel to decide if any sanction is necessary.

"I think it was out of character - we've not seen that kind of behaviour from him before. I'm delighted James has made the statement. "