Mal Brough is under renewed pressure to explain his role in the torrid Peter Slipper affair, with Labor escalating its attack and Clive Palmer reviving sensational claims the Special Minister of State asked him to fund a $200,000 legal case to "destroy" his political rival.

Mr Palmer was a long-time member of and major political donor to the Liberal National Party before he quit in protest and formed the Palmer United Party.

Under parliamentary privilege, Mr Palmer told the House of Representatives on Wednesday that Mr Brough asked him in April 2012 to fund Mr Ashby's legal case, which he said to he understood to be worth around $200,000.

Mr Brough won the Queensland seat of Fisher from Mr Slipper at the 2013 election.