A group representing post office licensees has defended links to a fringe political party accused of racism, anti-Semitism and conspiracy theories.
Licensed Post Office Group copped bipartisan criticism at a Senate hearing on Tuesday over links to the Australian Citizens Party.
LPO Group executive director Angela Cramp said it was great to receive support from the party.
"I have no understanding of what the citizens party represents. They are citizens of Australia. They are aligned with us," she told the hearing.
Liberal senator Sarah Henderson asked why LPO Group's campaign to phone ministers' offices urging for former Australia Post boss Christine Holgate to be reinstated was aided by the party.
"I am questioning why you would be working with an organisation known to be anti-Semitic, racist and also with many of its policies' foundation in conspiracy theories," she said.
LPO Group chair Andrew Hirst said while some Australians may find anti-Semitism offensive, equally others could be against the federal government paying over the odds for land near Western Sydney Airport.
He said the party contacted them offering advice rather than LPO Group asking for help.
Senator Henderson said his response was deeply concerning.
"The racist nature of this group really concerns me," she said.
Labor senator Kimberley Kitching urged the post office licensees to research the party's links to banking conspiracies and anti-Semitism.
The Australian Citizens Party was formerly known as the Citizens Electoral Council.
Ms Cramp also denied an LPO Group tweet calling Australia Post chair Lucio Di Bartolomeo "Lucio Di Bolognese" had racist overtones, saying her business partner was Italian.
But she agreed to apologise if he was offended.
Senator Henderson also suggested LPO Group represented between 11 and 25 per cent of post offices.
Ms Cramp said she would take the number on notice.