Transport Minister Phil Twyford has offered to resign for making a phone call on a domestic flight after the aircraft doors had shut in preparation for take-off.

Mr Twyford issued a statement today, saying he offered his resignation over the matter but the Prime Minister declined his offer.

"I recognise that I made the call when I shouldn’t have," Phil Twyford said. "This is inappropriate for anyone, but particularly inappropriate for me as Transport Minister.

"I apologise unreservedly.

"I have apologised to the Prime Minister and offered my resignation as Transport Minister. She has declined my offer but chosen to transfer my responsibility for the Civil Aviation Authority to Associate Transport Minister Julie Anne Genter.

"I have referred the matter to the Civil Aviation Authority who will follow whatever processes they deem appropriate," Phil Twyford said.

Speaking to media at Parliament Mr Twyford revealed that it was National MP Judith Collins who brought the issue before the House and he hadn't given it a moment's thought before she brought it up.

He again gave an unreserved apology while fronting media saying he "made a mistake" and his actions were "unacceptable".

Mr Twyford also revealed the call was made to a staffer and was around one minute long. He didn't reveal the details of the call and why it was so important to make at the time.