National is standing by embattled MP Maggie Barry after explosive allegations of bullying against staff.

Leader Simon Bridges wasn't available for interview yesterday, but a National Party spokesman said Barry "has the support of the National Party" and "is an effective and hardworking MP".

The Herald on Sunday can reveal more details of claims made against the North Shore MP and former host of Maggie's Garden Show.

Those allegations include Barry joking about a staff member's appearance at a public event and instructing him to keep a file on a political opponent.

The claims about Barry come in the same week that Speaker Trevor Mallard announced an independent review into bullying and harassment at Parliament.

Barry's former staff member went public after feeling dissatisfied with National's response to his concerns. Asked if National's response had been adequate, the spokesman said it wasn't appropriate to comment on individual employment matters.

"It is important however that should staff have concerns they feel free to raise them and the National Party recently sought assurances from Parliamentary Service that we have the right processes in place."

Further details about the claims made against Barry - all denied by the MP - are outlined in a document by Parliamentary Service, summarising a meeting with her former staffer.

The manager from Parliamentary Service, which employs staff who work for MPs, was told Barry made demeaning comments about some staff in the presence of others.

Those included allegations that she said, in a meeting with others present, the former staffer's moustache "was so 70s and had to go", which made him feel "the butt of her joke".

On another occasion the staffer joined Barry at a campaign stop at a retirement village in Northcote. Barry is alleged to have told the audience they could get a handout from "the man down the back dressed like the Great Gatsby".

The former employee claimed Barry asked staff to keep files on political opponents, including Miriam Clements, a Logic Party member who contested North Shore and believes the area should be completely independent from the rest of the country.

"Maggie would send me clippings and tell me to add them to the file on 'that crazy woman'," he alleged.

The worker is one of two staffers in Barry's four-person office to have accused her of bullying since May.

Neither staff member now works for Barry. During its investigations in August this year, Parliamentary Service heard allegations including that Barry expected staff would do work for the National Party during office hours.

Barry disputes all allegations and said Parliamentary Service had looked into them and "there was no finding that bullying or harassment had occurred".

"The issues have all been resolved professionally and by mutual agreement. I have wished the employees concerned well and so I am surprised they are being repeated in a partial, selective and incomplete way," she said.

Meanwhile, broadcaster Jesse Mulligan said he plans to respond on tomorrow night's The Project television show to comments from Barry labelling his conservation advocacy "pathetic".

Recordings were made by a former employee of Barry include one where she appears to discuss Mulligan's "really heavily opinionated" interviewing style, saying she doesn't care what he thinks and "his conservation stuff was pathetic".