Lambie offered secret union report brief

Independent senator Jacqui Lambie was offered a briefing on a top-secret unions royal commission report, but Tony Abbott denies it was a bargaining chip for her vote on a controversial bill.

She has demanded the report and the construction union's deregistration in return for her backing the re-establishment of the building industry watchdog.

In a letter dated August 12 to Senator Lambie, the prime minister doesn't offer to disclose the volume but allows for a confidential briefing by his department.

But a spokesman for Mr Abbott on Tuesday dismissed suggestions the deal was made in return for the senator's vote, saying in a statement there was nothing "transactional" about the proposal.