South Australian senator Cory Bernardi has officially quit the Liberal Party to establish his own party, using a scathing speech to criticise colleagues for "failing the people of Australia".

Key points: Senator Bernardi says he was reluctant and relieved to the leave the party

Senator Bernardi says he was reluctant and relieved to the leave the party He says it's time for a "better way, for a conservative way"

He says it's time for a "better way, for a conservative way" Coalition ministers turn on Senator Bernardi, describing his actions as "a betrayal"

The senator informed Prime Minister Malcolm Turnbull of his decision to defect shortly before a church service on Tuesday morning, which marked the start of the parliamentary year.

In a speech to colleagues, Senator Bernardi said he was reluctant and relieved to leave the party, saying the decision had "weighed heavily on his heart".

"The level of public disenchantment with the major parties, the lack of confidence in our political process, and the concern about the direction of our nation is very, very strong," he said.

"This is a direct product of … the political class being out of touch with the hopes and aspirations of the Australian people."

Senator Bernardi said his calls to restore faith in the political system had been ignored by some of his Liberal Party colleagues.

Sorry, this video has expired Cory Bernardi confirms he is leaving the Liberal Party to establish his own party

"It really is time for a better way — for a conservative way," he said.

Senator Bernardi said his new party, the Australian Conservatives, would focus on limiting the size of government and provide hope to "those who despair at the current state of Australian politics".

The 47-year-old senator has been a controversial figure in the Liberal Party and is known for his inflammatory remarks on gay rights, Islam and climate change.

He said the Government's position on energy and climate change was one reason behind his decision to leave the party.

'It's not your ticket to really hand over'

Senator Bernardi has been a controversial figure in the Liberal Party. ( ABC News: Nick Haggarty )

Coalition ministers have turned on Senator Bernardi, describing his actions as "a betrayal", with some calling on him to resign from politics.

Education Minster Simon Birmingham said the defection was "a dog act" and thousands of South Australians may be rethinking their vote.

The ABC understands Mr Turnbull told the partyroom he asked Senator Bernardi why he was leaving so soon after the election, describing his response as "not satisfactory".

Attorney-General George Brandis said Senator Bernardi had not acted like a conservative and had broken a promise to his electorate by leaving the party.

"Breaking faith with the electorate, breaking faith with the people who voted for you, breaking faith with the people who have supported you through thick and thin for years, is not a conservative thing to do," he said.

Defence Industry Minister Christopher Pyne called on Senator Bernardi to resign and recontest as an independent.

Deputy Prime Minister Barnaby Joyce said volunteers who worked for Senator Bernardi during the election campaign should be upset with his decision to leave the party.

"All the people who are in the Liberal Party who handed out his how-to-vote cards will ring him up and say, 'I handed out for the Liberal Party, I didn't hand out for the Cory Bernardi party,'" he said.

"It's not your ticket to really hand over, it's sort of ours."

When asked what advice he had for Senator Bernardi, Mr Joyce said he should "pray, pray hard".

Treasurer: We won't be distracted

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 7 minutes 24 seconds 7 m Scott Morrison on Cory Bernardi leaving the Liberal Party ( Leigh Sales )

Treasurer Scott Morrison insisted the Government would not be distracted by Senator Bernardi's defection, suggesting it would do little to ease concerns in the electorate.

He acknowledged concerns that mainstream politicians were not addressing issues such as housing affordability, jobs, electricity prices and childcare.

"People are worried that the mainstream parties are not addressing those concerns," he told ABC's 7.30.

"No change of personalities and [the] politics of Cory Bernardi, or anything else, is going to address those concerns — the Government can address those concerns and that's what we are doing."

Mr Morrison said he believed the Government could rely on support from Senator Bernardi in the Upper House.

"Before the last election, Senator Bernardi Gave his commitment to preselectors to be a Liberal in the Parliament, he gave his commitment to Liberal voters at the election…" he said.

"He also signed up to the platform we took to the last election when he was elected for a six-year term.

"There has been no change to that platform."

Party members, voters 'rightly disappointed'

In a statement, former prime minister Tony Abbott said he was disappointed at Senator Bernardi's decision and said more should have been done to keep him in the Liberal Party.

"While Cory and I have sometimes disagreed, I'm disappointed that more effort has not been made to keep our party united," he said in a statement.

"Cory Bernardi has made an important contribution to our public life and I deeply regret his decision to leave the Liberal Party."

Liberal MP Andrew Hastie said he considered Senator Bernardi "a good friend" but was disappointed he did not attend the party conference on Tuesday morning.

"I wish that he had attended the Liberal partyroom meeting this morning, looked us all in the eye and explained his reasons," he said.

"He was elected as a Liberal Party senator and owes his colleagues an explanation. Party members and voters will be rightly disappointed."