Deputy Liberal Leader Julie Bishop has slapped down Tony Abbott's changing opinions on climate change following his controversial key-note speech to sceptics in London this week.
Ms Bishop, who is in South Korea for security talks, said the former prime minister was entitled to express his views on global warming but pointed out they were vastly different to when he was in power.
Mr Abbott supported the Paris Climate Agreement while he was prime minister, set national emissions targets and established the Renewable Energy Target.
"I think the question that has to be asked of Tony Abbott is why does he have a different view now than when he was prime minister," Ms Bishop told the ABC on Thursday evening.
"He is entitled to change his mind, but I am sure that is why there is a deal of interest in what he has to say."
Ms Bishop steered clear of questions about whether Mr Abbott was going to lose the next election for the coalition with his constant undermining of Malcolm Turnbull, or whether he ought be expelled.
The foreign minister's intervention came after former Liberal leader John Hewson urged Mr Turnbull to stand up to Mr Abbott.
Dr Hewson believes the prime minister should call out his predecessor, especially over energy policy, which Mr Abbott focused on during his London speech.
"How long do you want to sit back and be beaten up, because that's what (Mr) Abbott's doing," he told Fairfax Media on Thursday.
Mr Turnbull should draw a line in the sand in adopting a progressive clean energy target in the full knowledge that Mr Abbott would fight back, he said.
Dr Hewson thinks Mr Abbott would "make a bit of noise" and "a few that would back him", but ultimately voters would appreciate the prime minister standing up for his beliefs.
"It's time for Malcolm to just take a stand and I think the electorate is looking for him to show leadership on so many issues," he said.
Cabinet minister Christopher Pyne doesn't see any point in getting into a "tit-for-tat" exchange with Mr Abbott.
"He's entitled to his views. He can argue his views in the court of public opinion," he told ABC radio.
Treasurer Scott Morrison and Education Minister Simon Birmingham both batted away questions about Mr Abbott on Thursday.
"I bet your viewers care more about their electricity bills than Tony Abbott," Senator Birmingham told the Nine Network.
© AAP 2017