Former prime minister Tony Abbott claims Treasurer Scott Morrison had "conveniently forgotten the very vigorous discussion" about immigration in 2015.
Tony Abbott has launched an extraordinary online attack on Treasurer Scott Morrison after the former prime minister called on the federal government to reduce its immigration rates.
Mr Abbott, who Mr Morrison served under as immigration minister, said the treasurer had "conveniently forgotten the very vigorous discussion about cutting immigration that took place inside government in early 2015 as part of the budget process".
"Because we were achieving a reduction anyway I eventually decided not to adjust the official figure but I kept it on the table as I never accepted the Treasury orthodoxy that more migrants meant more growth and a stronger budget outcome," Mr Abbott wrote in a post on his Facebook page.
"If Treasury is right why not solve the deficit simply by ramping up immigration?
"I repeat, we should not let Treasury's accounting rules stop the government from acting in our medium term national interests and Scott should have the gumption to think for himself."
Earlier on Thursday, senior colleagues defended Mr Morrison against another attack from Mr Abbott who suggested the Treasurer had been "captured" by his department on migration.
Acting prime minister Mathias Cormann has hit back at Mr Abbott's criticism of Mr Morrison's claim that reducing Australia's permanent migration level from 180,000 to 110,000 a year would wipe $5 billion off the budget over four years.
"Tony Abbott is wrong. To criticise the experts and say that somebody who is not an expert knows better is not the right approach," Senator Cormann told ABC radio on Thursday.
His cabinet colleague, Steve Ciobo, also rejected claims immigration is driving up house prices as a "palpably absurd statement".
It was a great shame to often see immigrants having "the finger of blame" pointed at them, Mr Ciobo said.
"I could not disagree more strongly with Tony Abbott's comments," he said.
Mr Abbott was not happy with Mr Morrison's arguments against his idea on Wednesday, claiming his former immigration minister was wrong and had been captured by Treasury.
Mr Morrison said Mr Abbott did not raise the issue of cutting migration to reduce house price pressure when he was prime minister and housing affordability was also an issue then.
- with additional reporting from Louise Cheer