Two industry groups have lodged an appeal against the controversial merger of the national construction and maritime unions.
The Fair Work Commission on Tuesday approved the three-way tie-up of the Construction, Forestry, Mining and Energy Union, the Maritime Union of Australia, and the Textile, Clothing and Footwear Union of Australia.
A spokesman for resources and energy group the Australian Mines and Metals Association said it had joined with the Master Builders Association to lodge an appeal against the decision.
The spokesman said the application was lodged with the Fair Work Commission on Thursday afternoon.
The employer groups are also seeking a stay on the commission's decision to approve the merger, which would stop the unions from merging until the appeal is decided.
The Master Builders Association said the merger would "put the economy and jobs in jeopardy”.
"The creation of a militant 'super union' is a backwards step that will have far-reaching consequences for the construction industry and the community,” chief executive Denita Wawn said.
CFMEU national secretary Michael O’Connor said the new union would be fighting to "restore the fair go" and would focus on turning the country around through a change of government.
Workplace Minister Craig Laundy on Tuesday called on leaders of the new body to act "responsibly and reasonably" and predicted "if their track record is anything to go by I wouldn't be surprised if there was magnified chaos".
The new union will have 144,000 members with an estimated $310 million in assets and annual revenue of nearly $150 million.
Mr Laundy vowed the Turnbull government would not give up on proposed laws that would impose a "public interest test" on union mergers. The government's legislation has stalled in the Senate because Labor, the Greens and a number of crossbenchers oppose it.
Former Employment Minister Eric Abetz congratulated the Master Builders and AMMA for launching an appeal against the merger.
“This unholy alliance of law-breaking union heavies is a real concern for the millions of Australians who support the rule of law,” Senator Abetz said.
“The decision by the Master Builders and AMMA to appeal the decision is very welcome and I encourage the government to intervene in the case on the side of common-sense and to urgently advance the consideration of the previously introduced legislation.”