Internal Affairs Minister Richard Worth last night vehemently denied Labour suggestions that his "personal expenses" on a trade trip he led to India in February as chairman of the India Trade Group were privately paid for him.

He accused Labour MP Pete Hodgson of "an incredible abuse of parliamentary privilege" and said his suggestion would be defamatory if he repeated it outside Parliament.

"It is quite scandalous, really, and I find it upsetting."

Dr Worth said he had led three not-for-profit business councils promoting trade - the India Trade Group, the Korea-New Zealand Business Council and the Hong Kong-New Zealand Business Association - "and I have always paid my own way."

After his resignation from New Zealand Aviation on Monday, Dr Worth resigned as director from two more companies yesterday.

One of them, the Indian Overseas Group Ltd, had three National MPs as directors - Trade Minister Tim Groser, list MP Kanwal Jit Singh Bakshi and Dr Worth.

The three are believed to still be shareholders pending the company's removal from the companies register.

Dr Worth said last night he had resigned directorships he held with all companies.

"I have resigned from everything, absolutely everything."

As is required for ministers, Dr Worth received Prime Minister John Key's approval for the private overseas trip.

But he did not declare he was a director of New Zealand Aviation, which is in a joint venture with an Invercargill flying academy and which secured a flight training deal in India.

Dr Worth was also quoted in Indian media as promoting New Zealand for its flight training skills.

Mr Key has said he would not have approved the trip had he known those facts, although he did not believe Dr Worth sought to mislead him or had made any personal financial gain.

Labour leader Phil Goff led the offensive in Parliament yesterday, describing the trip as a "private business junket run" run by one of Mr Key's ministers.

Mr Key deflated his attack by declaring that one of the honorary advisers to the India Trade Group was Mr Goff himself, a former Trade Minister.

But Mr Hodgson led the more scandalous allegations, asking: "Were his fellow shareholders in New Zealand Aviation ... among those who contributed $1000 per person towards his personal expenses. If so, how much did the trip to India cost him, or might he have run it at a small but tidy profit?"

Dr Worth said in Parliament: "I am simply unaware of the truth of that statement. I do not believe it to be correct."

He later checked with the Indian Trade Group's chief executive, Mr Giri Gupta, and secretary Mr Bhavdeep Dhillon, and emphatically denied having received any such funding.

Mr Gupta and Mr Dhillon are also the remaining directors and shareholders of NZ Aviation, and are also fellow directors and shareholders of the Indian Overseas Group Ltd - the company with a similar name to the not-for-profit Indian Trade Group.

Dr Worth had two fellow MPs on the delegation, Mr Bakshi and Invercargill MP Eric Roy.

Others included Waitakere City Council chief executive Vijaya Vaidyanathan, Waitakere international relations manager Richard Duncan, and Southern Institute of Technology international manager Bharat Guha.