Just how National got its hand on Budget documents before the Government's announcement could soon become clear.

The Herald understands National intends to reveal how it acquired the documents tomorrow - on Budget Day.

Today, the Government went to pains to put distance between any suggestions it had accused National of having any part in the unlawful hacking of the Treasury's website.

Both inside the House and talking to media this afternoon, Prime Minister Jacinda Ardern and Minister of Finance Grant Robertson were fending off accusations the Government had smeared National.

Last night, Treasury said it had "gathered sufficient evidence to indicate that its systems had been deliberately and systematically hacked".

The matter was referred to the police on the advice of the National Cyber Security Centre – an arm of the GCSB.

Treasury Secretary Gabriel Makhlouf said this morning there had been 2000 hacking attempts on the Treasury website.

On Tuesday, National released information that Finance Minister Grant Robertson admitted was, in fact, part of Budget 2019.

In a late night press release on Tuesday, Robertson asked National not to release any further material, "given that the Treasury said they have sufficient evidence that indicates the material is a result of a systematic hack and is now subject to a police investigation".

Bridges took exception to this, saying Robertson had clearly implied National had hacked Treasury, or had received hacked information.

"Grant Robertson has made scurrilous false allegations. He has smeared the National Party," Bridges told media this morning.

"There has been no hacking under any definition of that word. There has been entirely appropriate behaviour from the National Party.

"There has been nothing illegal or even approaching that from the National Party at any time."

Bridges said he had not sought legal advice on the issue, as he said he wouldn't need it, and declined to say if he would resign if it turn out the information was obtained unlawfully.

Although legal experts have shared their opinions about whether or not the information was acquired illegally, it won't be known until the police have finished its investigation.

Robertson said today he did not have a timeline on that, but it's likely the process would take months.

Before going into the House, Robertson was unable to go into much detail regarding how he thought the information got into the hands of National as, he said, the matter was the subject of a police investigation.

But he did deny that he had linked the hack to the National Party.

"What we did last night was indicate to the National Party that we had said to the National Party we thought it would be a good idea if they didn't release any material, given what the Treasury had told us."

He denied this was effectively an accusation against National.

"Nobody has actually made the accusation, in that way."

In the House, Prime Minister Jacinda Ardern agreed.

"What I think we need to make sure is absolutely clear here is that no one has made a direct accusation to the National Party. It is now the subject of a police investigation and it is not for us, therefore — it would be inappropriate — to make an accusation against the National Party."

But Deputy Prime Minister Winston Peters was not holding back when he spoke to media this afternoon.

He said the information obtained by National had been acquired illegally.

Asked if he had seen evidence which proved this, Peters said: "Of course".

When pressed on how he knew, Peters said it was "my job to know".

"Information came to them [National] in circumstances where the behaviour was totally illegal and they should have known it," Peters, said.

"All I can tell you, whilst I'm not prepared to go public with it, is … the facts look very, very bad for the National Party."

He said Bridges had "made a right fool of himself" and, although he has predicted Bridges downfall numerous times, Peters said he expected the National leader to be "gone-burger" as a result of the saga.

Timeline of the hacking saga:
Sunday: Treasury said that hacking attempts on the Treasury website began

Tuesday, 10:01am: In a press release, National publishes what it claimed to be details of the 2019 Budget

Tuesday, 11:30am: Finance Minister Grant Robertson confirms "some" of the details in the press release were from Budget 2019

Tuesday, 1:30pm: National releases more Budget details

Tuesday, 4:01pm: National reveals even more information it says is from the Budget, including details around funding for a mental health and wellbeing commission

Tuesday, 6pm: The Secretary of the Treasury, Gabriel Makhlouf received information that led him to refer the matter to the police

Tuesday, 7pm: Makhlouf informed Finance Minister Grant Robertson he had referred the matter to the police

Tuesday, 7:20pm: Prime Minister Jacinda Ardern was informed of the situation

Tuesday, 8:02pm: Treasury issues press release saying it had "sufficient evidence" that it had been hacked

Tuesday, 8:19pm: Grant Robertson issues a press release, asking National not to release any further information

Wednesday, 7:04am: Makhlouf said there had been 2000 hacking attempts in the 48 hours after Sunday

Wednesday, 9am: Simon Bridges strongly denies the information National released came into its possession unlawfull