The psychiatrist and columnist Tanveer Ahmed has been sacked by the Australian for plagiarism – just two years after being dropped by the Sydney Morning Herald for a series of similar cases.

Ahmed was exposed by ABC TV’s Media Watch in 2012 and consequently lost his regular spot as a commentator for Fairfax Media.

On Monday the blogger Ketan Joshi accused Ahmed on Twitter of plagiarising the US political website Prospect in his latest article for the Australian, a controversial opinion piece on domestic violence.

The editor of the Australian, Clive Mathieson, told Guardian Australia he became aware of the accusation on Monday.

“When the Australian discovered it, we discussed it with Tanveer Ahmed and it was decided he would no longer be writing for us,” Mathieson said.

Ahmed wrote in the article: “…it is critical that improving arrest and prosecution rates, establishing shelters and abuse hotlines, pushing for state provisions against stalking, and creating protections for immigrants all have the goal of getting victims out of abusive relationships.”

The Prospect article said: “Improving arrest and prosecution rates, establishing shelters and abuse hotlines, pushing for state provisions against stalking, and creating protections for immigrants all have the goal of getting victims out of abusive relationships and into safe situations.”

On his blog, Joshi presented more allegations of plagiarism in Ahmed’s work, including from the Medical Journal of Australia, and of recycling of Ahmed’s own work.

Ahmed was already the subject of a heated debate about domestic violence because his article argued that male disempowerment was partly to blame for domestic violence.

“Gender relations have changed dramatically in the past few decades, but discussions about family violence are stuck in the mindset of 1970s radical feminism,” he wrote.

On Tuesday the White Ribbon campaign announced that Ahmed had agreed to step down as an ambassador following the outcry over his article in the Australian. His views expressed in the article and in subsequent comments were “inconsistent with the message and focus of the White Ribbon campaign”, it said.

Joshi told Guardian Australia he was so offended by Ahmed’s views he used online tools to check his work for plagiarism.

Joshi said he was particularly angry about a paragraph that linked family violence to ethnicity.

”Family violence within newly arrived ethnic groups is often related to the sudden dilution of traditional masculinity, leaving men lost and isolated, particularly as females enjoy greater autonomy and expectations,” Ahmed wrote.

On Tuesday morning Ahmed said on Twitter the latest plagiarism case was “inadvertent” and the reaction felt “brutal”.

I accept my past and that I had little room for error. But this case is inadvertent. Feels brutal. @meadea @ErikOJensen — Tanveer Ahmed (@drtahmed) February 16, 2015

When Ahmed was caught by Media Watch in 2012, he did not give up his public profile, writing a piece on the plagiarism incident for the Australian soon after and then recording an interview with Radio National’s Media Report in which he admitted he knew cutting and pasting was wrong, but did it anyway.

“There was definitely a time there where I knew what I was doing was wrong,” Ahmed told the Media Report.

“And essentially I did it anyway. And the way that would have happened is that I don’t think…I think I’d lost sight of the magnitude of what I was doing. I think it felt like a fairly minor transgression for me. But I think in terms of my self-audit, I think that’s how it happened.”

He promised to return to writing but said he would do it differently and stick to subjects “closely tied to my expertise”.

“Do it with real purpose rather than being part of say, a kind of a comment monster, that it needs to be fed. Where I’m kind of feeding this media monster of comment.”