Pauline Hanson’s One Nation is facing growing scrutiny from election authorities as one of its former senators produces an explosive document that claims the party signed up supporters who were not really members.

The party’s former NSW senator, Brian Burston, has written to the NSW Electoral Commission to urge an investigation into an alleged “breach of process” at One Nation when it set up its state division.

The move challenges Senator Hanson’s successful bid earlier this year to establish a fully-fledged NSW party in time to fight the state election in March, amid rumours she wants former federal Labor leader Mark Latham to be her lead candidate.

Brian Burston quit Pauline Hanson's One Nation party last month and now represents the rival United Australia Party set up by billionaire Clive Palmer. Credit:Alex Ellinghausen

In a sign of Mr Latham's support for One Nation, he recorded a message to help the party in the July 28 byelection in the Queensland marginal seat of Longman, telling voters not to trust Opposition Leader Bill Shorten.