A key ally of Labor leader Bill Shorten likened a blond Liberal senator to a Hitler Youth member before swearing and calling him a 'poor petal' when he took offence.
Tensions in a parliamentary estimates committee heightened when veteran Senator Kim Carr, a Labor frontbencher, made the slur.
'You'd know that - those in the Hitler Youth would understand that only too well,' he said during the Thursday morning clash between the two Melbourne-based senators.
Labor Senator Kim Carr called his much younger Liberal opponent James Paterson (pictured) a Hitler Youth member during a parliamentary committee clashiPhone transfer software
Senator James Paterson, 30, immediately took offence during a committee hearing at Parliament House in Canberra on the otherwise dull topic of research.
'That is outrageous, Senator Carr. That is seriously, seriously offensive,' he said.
Upon being asked to withdrawn the remark Senator Carr, 62, argued he was 'being facetious' before continuing to insult the Liberal senator who is half his age.
Senator Paterson said it was 'not facetious' to liken someone to a Hitler supporter.
'Accusing someone of being a Nazi is a very serious thing,' he said.
Senator Carr continued throwing barbs as he withdrew the remark.
'You'd know that - those in the Hitler Youth would understand