Barbara Ramjan, who says she was intimidated by Mr Abbott, and the barrister, David Patch, who came forward this week to back her recollections, both hit back at Mr Abbott yesterday, saying they stood by the story and Labor had nothing to do with it.

So, too, did the publication, the Quarterly Essay, which sparked the row when it published the anecdote this week in an essay on Mr Abbott by the former Herald journalist, David Marr.

''This is a clear case of trying to shoot the messenger,'' the publishers said. ''The events described were discovered by the journalist David Marr during his extensive research'', and theories about a dirt unit were ''completely implausible''.

Marr, who studied law at Sydney University, said he heard the story at a 40th reunion while researching the essay. Ms Ramjan recounted that after she beat Mr Abbott in the 1977 Student Representative Council elections, he put his face close to hers and punched the wall on either side of her head.

Fronting the media yesterday for the first time in almost a week, Mr Abbott sought to reconcile his previous statements that he could not recollect the incident and that it never happened. ''How can you recall something that never happened?'' he said.

He did admit to another allegation - that after Ms Ramjan became the SRC chairman and asked to be known as chairperson, he called her ''chairthing''.

''There were lots of silly, embarrassing, childish things done in student politics and I wasn't immune to that,'' he said.

Mr Abbott denied the wall-punching allegation and claimed the matter had been dredged up by a Labor dirt unit. ''There is a Labor dirt unit and it's feeding information to people left, right and centre,'' he said.

Ms Ramjan, who has been telling the story for years, told the Herald it was ''absolutely'' true and she rejected outright that Labor put her up to it. ''I have never been a member of a political party in my life,'' she said. ''He's a bully.''

Mr Patch, now a barrister and Ms Ramjan's campaign manager in 1977, recounted in an article for the Herald this week that he was nearby when the alleged incident occurred. He said a scared and angry Ms Ramjan approached him just afterwards. ''[Ms Ramjan] told me that Tony Abbott had come up to her, put his face in her face, and punched the wall on either side of her head. So I am a witness,'' he said.

Mr Patch, who was the Labor candidate for Wentworth in the 2004 election but now describes himself as ''just'' a Labor member, stridently rejected Mr Abbott's claims his comments were driven by a dirt unit.

''I can categorically deny that I have had any contact, either directly or indirectly, with anyone in or associated with the Labor Party,'' he said about his decision to go public. ''I spoke to Barbara Ramjan about it, that's all.''

Mr Patch rang the Herald wanting to write a letter to the editor after reading piece in Tuesday's Herald by columnist Gerard Henderson defending Mr Abbott and questioning Ms Ramjan's recollection.

The Herald asked Mr Patch if he would like to write for the opinion page. The next day, the Herald offered Mr Abbott an opinion piece but he declined.

The Education Minister, Peter Garrett, said Mr Abbott ''can't have it both ways''. ''He can't talk about politics being a test of character and then, when his own character is under test, run away,'' he said. ''I don't think Mr Abbott can swat it away like it's a blowie on a summer's day.''