Silence from Christopher Luxon, David Seymour over Winston Peters' March 15 tweet

New Zealand First leader Winston Peters is doubling down on his claim former Prime Minister Dame Jacinda Ardern concealed details about the Christchurch terror attack.

On social media he said, the country only discovered on Wednesday that her office had received information about the attacks before it happened. In reality, Ardern released that detail two days after the attack.

The Islamic community's slammed it as political posturing, but Peters' potential coalition partners are refusing to comment.

March 15 was one of New Zealand's darkest days, marked by political unity.

"We want to ensure that this is a unified political response that is beyond politics," Peters said at the time. 

He was the deputy Prime Minister when the attacks happened and he stood by Dame Jacinda in that response - until now.

The ongoing coronial inquest into the attacks on Wednesday heard evidence about the gunman's manifesto being sent to the PM's office.

Peters followed that up with a tweet, claiming: "We waited until today to find out, for the first time, that the Prime Minister's Office received information about the March 15 terrorist attack before the massacre took place.

"Jacinda Ardern should be called to the hearing and asked to explain this appalling lack of transparency to the New Zealand public - let alone to the Deputy Prime Minister and government coalition partner. 

"This was a crisis event. To keep this basic information hidden is not only unacceptable, it is now clearly indicative of how that office worked. The next question is who else inside Cabinet knew and said nothing?"

But Peters got this totally wrong - because just two days after the attack, Dame Jacinda told New Zealand: "I was one of more than 30 recipients of a manifesto that was mailed out nine minutes before the attack took place."

That detail was also in the Royal Commission of Inquiry into the attacks.

Abdur Razzaq, spokesperson Federation of Islamic Associations of New Zealand, said it was there in black and white. 

"It's obvious [Winston Peters] hasn't even read the Royal Commission - and for a senior statesman!"

The Prime Minister's Office has urged Peters to remove his tweet and post a correction.

But Peters instead chose to double down, posting late on Wednesday night. 

"For those political apologists and feckless media, there is an existing transcript of a phone call made by the Prime Minister to the Deputy Prime Minister at the vital time of a crisis when a terrorist had just massacred innocent people. 

"Not once were we transparently informed of this information - such as the phone call her office made to the police - despite the obvious expectation and clear opportunity. 

"To excuse it because it was known at a 'public press conference' the next day, instead of information that should've been shared with the Deputy Prime Minister and coalition partner the day before, is as bizarre as it is biased."

Peters then tweeted on Thursday afternoon his initial comment was about the location of the attacks.

"What is more important?" asked Razzaq. "To learn the lessons of March 15 or political posturing for a short media burst? I think that sort of political tweeting, you can leave it in Trump's America."

But in National Party leader Christopher Luxon's New Zealand, where he's trying to form a government that may include New Zealand First, there was silence.

ACT leader David Seymour also refused to say a peep, while Peters wouldn't be interviewed.

The last Kiwis have heard from the man about to lead them was a tweet about the All Blacks on Wednesday night.

Luxon on Wednesday morning said all was going well with coalition talks. 

"I think it's important that we get a good foundation of good chemistry, of good trust, of good relationships, in place."