Associate Health Minister Casey Costello has defended herself against claims she tried to freeze excise tax on tobacco, reminding the public that she actually raised the excise tax by 5.64 per cent only two months ago.

During an interview this morning on The Mike Hosking Breakfast, Costello noted that, "People seem to forget that the first thing I did as Minister of Customs was raise the excise tax by 5.64 per cent in November.".

"It’s just a broad document ... there’s no involvement from Big Tobacco, this is just nonsense," she said.

When speaking during Question Time on Thursday, Costello doubled down on her stance, maintaining she had not specifically asked for the advice, and she had not written the documents she sent to officials.

“The documentation is a range of historical policy positions and notes that were held in New Zealand First policy positions. Some of it relates to things that were passed in the legislation when New Zealand First was in government. This is a range of points and positions and it’s about five pages long.”

She said her actions had been distorted by the media.

“The fact is, I was asked a question about whether I had sought specific advice. I had not sought specific advice, which was the question I answered. I referred to a range of advice I had sought from officials,” she said.

Costello said she was unsure who wrote the documents.

Labour’s health spokeswoman, Dr Ayesha Verrall, said the minister was still responsible for the documents she presented, and the Prime Minister should relieve Costello of her duties.

“When a minister gives documents to officials, if that is done or collated by her office it is still her responsibility. Her office acts on her behalf, she needs to take responsibility for it.”

Senior National Party minister Chris Bishop said that while ministers were responsible for things they gave officials, there was a question over whether they were responsible for the generation of that material.

“I would argue they cannot be, in the same way that if, for example, a Labour Party minister gave a document to the Ministry of Education, that was the NZEI or the PPTA or the CTU, for example, they cannot be questioned about the CTU in Parliament.

“They can be questioned about the handling of that document and what’s in the document, but the generation of that document I think would fall outside the scope of ministerial responsibility.”

Speaking to media after Question Time, he said the matter of the authorship of New Zealand First’s policies was for Costello to answer, but he had certainly presented party policy to officials.

He said talking to a range of groups was how the country gets good policy.

“People have easy access to ministers and MPs in New Zealand. All political parties work with a range of groups when it comes to developing policy.”