Should PM know why minister quit?

There was no need for Prime Minister John Key to know why a minister was resigning, he says.

Questions have been raised about whether Mr Key should have accepted ACT MP Heather Roy's resignation as a minister without knowing the reason for it.

There was a bust-up after ACT party leader Rodney Hide took a defence document from Mrs Roy's office, while she was associate defence minister and the party's deputy leader. Mr Hide said he was cleared of wrongdoing by Ministerial Services.

Mr Key said his office was made aware of the issues and that Ministerial Services decided there was no substance to the complaint.

"At that point I decided there was no further need for me to look at it."

The incident showed the breakdown in the relationship between Mr Hide and Mrs Roy, but, he said, that was a matter for ACT.

Mr Key said he had not seen the document under dispute but there were thousands of similar documents and he did not review them all.

When presented with Mrs Roy's resignation he had two options -- accept it or decline, Mr Key said.

Technically, Mrs Roy could have remained a minister without being deputy leader.

"The nature of our relationship with the ACT Party, as it is with our other support parties, is that we offer them ministerial warrants subject to their seniority."

Asked if he had a responsibility to ask why Mrs Roy was resigning, Mr Key said he did not need to.

"She offered her resignation because the caucus no longer had confidence in her."

Labour leader Phil Goff said Mr Key had a responsibility for all ministers and should have found out why Mrs Roy quit.

"Here we have a minister of the crown dismissed, no reasons given, no openness, no transparency, it's not good enough.

"This is the party that's propping up the Government."

The public deserved to know whether she was sacked for protecting the integrity of documents she was responsible for, he said.

Mr Hide said the caucus had made a decision to support John Boscawen as deputy leader, and he had no concerns about Mrs Roy's capabilities as minister.

"I've handled the whole situation as well as I'm able to and so has the caucus."

The party was going through a tough time, he said.

He never felt threatened by Mrs Roy as a leadership competitor and caucus had discussed a number of issues before voting for Mr Boscawen.

He would not discuss those details.

"I've expressed my hope and desire that Heather will have good break and come back and work her way back as an excellent MP."

ACT MP Sir Roger Douglas told NZPA he voted for Mrs Roy in caucus yesterday and still supported her.

He was sent to check on Mrs Roy this afternoon.

"I think all the caucus will be standing behind Heather and supporting her. A decision was made (yesterday) in terms in of deputy leadership, but the caucus members are bound to support one another."

Sir Roger said he believed Mrs Roy would return to Parliament after her two weeks' leave.

Mr Boscawen replaced Mrs Roy as deputy and took over her consumer affairs portfolio and an associate commerce role previously held by Mr Hide.

He was sworn in as a minister today.