Mr Abbott's dramatic decision late this afternoon has sparked a domino affect, with Victorian MP Sophie Mirabella also quitting.

There are now reports that fellow front benchers Senators Nick Minchin, Eric Abetz - both powerful Liberal party figures - and MPs Tony Smith and Stephen Parry have all resigned their posts.

It follows yesterday's resignations by Senators Mitch Fifield, Mathias Cormann and Brett Mason from their frontbench positions.

Mr Abbott told reporters it was not a leadership issue but a policy issue.

"This is an argument about policy. It is not an argument about the leadership," he said.

He said that he and Senator Nick Minchin had seen Mr Turnbull in his office after question time this afternoon to ask him to reconsider his policy on emissions trading and delay a vote on Labor’s emissions trading scheme until next year, after the Copenhagen summit.

They had proposed the matter be put to a Senate inquiry but Mr Turnbull had said he was not prepared to reconsider.

"I indicated to Malcolm at the end of the conversation that given his position I could no longer support the opposition’s policy and therefore could no longer be in the shadow cabinet,’’ he said.

He had no option but "to take the honourable course".

"It was a very civil, rational and courteous conversation conducted in a spirit of mutual respect," said Mr Abbott.

He said in the light of the fact he could no longer support his leader's policy he had no option but to resign.

"It is a very difficult decision for me," he said. "I have always been a very loyal party man."

Mr Abbott said his office had had an "absolute deluge" of critical emails after Mr Turnbull announced the coalition’s support for the amended ETS.

"The phone lines have been in meltdown with people saying that the Liberal Party would not be doing its job as an opposition simply to pass this thing without scrutiny ... it demands," he said.

Mr Abbott said it had been a "pretty heavy week" for the party.

"And for someone who has a record of loyalty to the party and to the leader that I’ve had, this has been an incredibly momentous decision."