The list of projects to be funded under the Coalition's controversial sport grants program was changed by the Morrison Government hours after last year's election was called, Parliament has heard.

Key points: The final list of approved projects was changed after Parliament was dissolved

The final list of approved projects was changed after Parliament was dissolved Labor is demanding the Prime Minister explain why changes were made after the election was called

Labor is demanding the Prime Minister explain why changes were made after the election was called The Coalition maintains the program was managed appropriately

Labor is using every opportunity during Senate estimates to grill the Government and senior public servants over the management of the pre-election grants process.

The revelations from a Senate committee late on Monday increase pressure on the Coalition over the $100 million sporting infrastructure scheme.

The National Audit Office's scathing report into the program in January found it was politically biased.

Auditors revealed worthy applications were binned in favour of projects in politically important seats.

The committee heard last-minute changes took place on April 11, 2019 — the day Scott Morrison called the election and both houses of Parliament were dissolved.

Sport Australia received a final version of a spreadsheet of projects for approval at 12:43pm, more than four hours after Parliament was shut down.

The update added nine projects, and removed one.

The Prime Minister's Office was sent the same spreadsheet 8 minutes earlier.

The now-infamous colour-coded spreadsheet linked clubs which should receive funding with the electorate they were in.

These changes were seemingly made after 8:46am that same morning, when an earlier version of the spreadsheet had been sent to Sport Australia.

The Government had gone into caretaker mode at 8:30am.

Katy Gallagher has demanded the PM explain his office's involvement. ( ABC News: Ian Cutmore )

Labor senator Katy Gallagher told AM the Government should explain why changes were made to what was considered the final approved list.

"The more evidence we get, the more we ask questions, the murkier and murkier this gets," she said.

Under decades-old caretaker conventions, governments should not make important decisions after calling the election.

Senator Gallagher said there were questions about whether lists should have been altered after Parliament had been prorogued. She also wants to know what say the Prime Minister had in the decision-making process.

Labor frontbencher Tony Burke went further and accused the Prime Minister of being caught spending taxpayers' money during an election campaign.

"[It's] without doubt that the Prime Minister has misled the Australian Parliament, he's misled the media, he's misled the Australian people. The gravity of the mislead is extraordinary," he said on Tuesday morning.

"The audit office have caught the Prime Minister out red handed.

"The caretaker provisions are there to stop governments from spending taxpayer money as if it belongs to their political party during a campaign."

Brian Boyd from the Australian National Audit Office said the spreadsheet was sent to the Prime Minister's Office. ( ABC News: Ian Cutmore )

Australian National Audit Office executive Brian Boyd said emails were exchanged between the office of then-sports minister Bridget McKenzie and the Prime Minister's Office on April 10 and April 11.

"There were responses both that day and into the following day as well as sorting out what the final list of approved projects would look like," Mr Boyd said.

"When I referred to one project coming out and one project coming in, in terms of the 8:46am version, that was at the request of the Prime Minister's Office."

Mr Boyd said there was no evidence the Prime Minister's Office was behind the last set of changes to the spreadsheet.

A document giving official approval for round three of the Community Sport Infrastructure Program grants, signed by then Senator McKenzie, was dated April 4.

The Government has pointed to that date to insist it did not breach caretaker conventions.

Labor has accused the Minister of deliberately backdating the decision.