Mr Abbott said the government would make an announcement about the scope of a promised judicial inquiry into union slush funds, while manager of government business Christopher Pyne confirmed a hardening of the Coalition's views as he confirmed a royal commission with sweeping powers was a "live option".

Employment Minister Eric Abetz said the government would attempt to pass its laws to restore the ABCC through the Senate on February 11, the first day of Parliament. Treasurer Joe Hockey said there is "mounting evidence that there are systemic problems in the union movement that need to be fully exposed and addressed".

And as officials from the Victorian and national branches of the construction union met in Melbourne to discuss the allegations of corruption and bribes, former ACTU leaders Bill Kelty, Simon Crean and Martin Ferguson weighed into the escalating stoush and lashed the minority of union officials who appeared to have broken the law.

The Coalition promised to restore the Howard-era construction watchdog as a "tough cop on the beat" before the election and the laws passed through the lower house, but Labor and the Greens have so far resisted pressure to pass the legislation in the Senate.

Mr Kelty told Fairfax Media there were "some problems" in the union movement, in his experience, but the "overwhelming behaviour of trade union leadership in my judgment was honest and ethical".