In an extraordinary admission last night, the Opposition Leader said his only utterances that should be regarded as ''gospel truth'' were carefully prepared and scripted remarks such as those made during speeches or policy pronouncements.

Otherwise, he indicated that statements he made during the ''heat of discussion'' such as radio interviews or under questioning at press conferences, were not necessarily reliable.

''I know politicians are going to be judged on everything they say but sometimes in the heat of discussion you go a little bit further than you would if it was an absolutely calm, considered, prepared, scripted remark,'' he said.

''Which is one of the reasons why the statements that need to be taken absolutely as gospel truth [are] those carefully prepared, scripted remarks.

''Most of us know when we're talking to people, or listening to people, when we can put absolute weight on what's being said and when it's the give and take of standard conversation.''

The admission, seized on by the Rudd government as a sign that nothing Mr Abbott says can be trusted, came during an interview on the ABC's 7.30 Report.

Mr Abbott had been asked to reconcile the promise he made during a radio interview in February that there would be no new or increased taxes under a Coalition government with his announcement a month later that the Coalition would lift company taxes by 1.7 per cent to fund a $2.7 billion paid parental leave scheme. He said the original promise was made in the heat of discussion.

''Some people will judge me harshly, I accept that. I understand that some of them will say 'Aha, he said this in a radio interview in February and then a month later … he made a commitment to paid parental leave which is not completely consistent with that first statement.

''All of us when we're in the heat of verbal combat, so to speak, will sometimes say things that will go a little bit further.''