Piers Morgan has quit as co-host of ITV’s breakfast show Good Morning Britain after critical remarks he made about the Duchess of Sussex’s mental health prompted an on-air row with a colleague and an Ofcom investigation. Pressure had mounted on Morgan since he made the comments on Monday’s edition of the show, which followed the airing of Meghan and Prince Harry’s tell-all interview with Oprah Winfrey in the US on Sunday night. The Guardian understands that a formal complaint was lodged with ITV on behalf of the duchess after the broadcast. By early evening on Tuesday, Ofcom had received more than 41,000 complaints about Morgan’s behaviour, prompting the broadcasting regulator to launch an investigation into whether his comments broke the UK broadcasting code relating to harm and offence. Just a couple of hour later, ITV released a statement saying: “Following discussions with ITV, Piers Morgan has decided now is the time to leave Good Morning Britain. ITV has accepted this decision and has nothing further to add.” In Winfrey’s interview, Meghan detailed how her mental health had deteriorated while she was pregnant amid a barrage of negative press and lack of support from “the firm” – the apparatus surrounding the royal household – which had repeatedly turned down her appeals for help and discouraged her from leaving the house for months. “It was all happening just because I was breathing,” Meghan said, breaking down in tears during the interview, which was broadcast on ITV on Monday night. “I just didn’t want to be alive any more. That was a clear, real, frightening and constant thought.” She told Winfrey she had asked to go somewhere to get help with these suicidal thoughts, but was told it would not look good by one of the most senior people in the institution of the monarchy. Morgan questioned on Monday’s edition of GMB whether she was telling the truth. “Who did you go to?” he said. “What did they say to you? I’m sorry, I don’t believe a word she said, Meghan Markle. I wouldn’t believe it if she read me a weather report.” The remarks provoked a backlash, and it is understood that ITV executives wanted Morgan to apologise for them on-air. During Tuesday’s programme Morgan said: “When we talked about this yesterday, I said as an all-encompassing thing I don’t believe what Meghan Markle is saying generally in this interview, and I still have serious concerns about the veracity of a lot of what she said. “But let me just state on the record my position about mental illness and on suicide. These are clearly extremely serious things that should be taken extremely seriously, and if someone is feeling that way they should get the treatment and help they need every time.” On the same show, Morgan stormed off set after a discussion about Meghan with his colleague Alex Beresford. The weather presenter defended the couple, telling Morgan: “I understand you’ve got a personal relationship with Meghan Markle, or had one, and she cut you off. She’s entitled to cut you off if she wants to. Has she said anything about you since she cut you off? I don’t think she has but yet you continue to trash her.” As Beresford continued, Morgan got up and stormed out of the studio, saying: “OK, I’m done with this, sorry, no, can’t do this.” Beresford called his behaviour “pathetic” and “diabolical”, while co-host, Susanna Reid, was forced to send the show to an early break. Beresford later tweeted of the discussion, in which he had also shared some of his own experiences of racism: “I wish I had the privilege to sit on the fence. In order for me to do that I would have to strip myself of my identity and that’s not something I can do. It’s not any of our places to pick apart claims of racism in order to make us to feel more comfortable.” ITV’s chief executive, Dame Carolyn McCall, subsequently said the row was not “manufactured”. McCall added that ITV’s managing director of media and entertainment, Kevin Lygo, had been in discussion with Morgan in recent days regarding his coverage of the Harry and Meghan interview. She said Good Morning Britain was a balanced show, adding: “ITV has many voices and we try and represent many voices every day. It’s not about one opinion.” Among those reacting to Morgan’s exit from GMB, where he has been co-host since 2015, was Lorraine Kelly, who presents the 9am show on ITV that follows it. She told the BBC’s The One Show that Morgan had only just emailed her to break the news and said she had “no real details”. “It’s certainly going to be quieter,” she said. “We all wish him well … Like I say, it will be calmer.” A statement issued by Buckingham Palace on behalf of the Queen on Tuesday said the royal family was saddened by the revelations made in the Oprah interview and the issues raised around race were “concerning”.