Business groups admit a royal commission into unions could also be uncomfortable for employers, as Labor and the ACTU call for a crackdown on “crook bosses” in the construction industry.

Federal cabinet is expected to sign off on the royal commission today, with Prime Minister Tony Abbott saying it’s necessary to “shine a great big spotlight” on corruption.

Industry groups including Master Builders Australia and the Australian Industry Group tentatively welcomed news of a broad inquiry into the unions.

But both have no doubt employers will also get caught up in the investigation.

“A royal commission will be uncomfortable for both employers and for unions because collusion takes two parties,” Master Builders chief Wilhelm Harnisch told ABC radio.

Companies were “unwilling partners” in the construction industry’s culture of corruption, he said.

Australian Industry Group chief executive Innes Willox conceded some of its members could be implicated through the commission.

“I don’t really know how far or wide the government is going to go,” he told ABC television.

“The thing about royal commissions is once you light the match, you don’t quite know where it’s going to go.”

ACTU boss Dave Oliver said there was no place in the union movement for corruption, but the commission must look at dodgy employers as well as unions.

“I’ve got no doubt there are crook bosses in the construction industry,” he told ABC radio.

The Construction, Forestry, Mining and Energy Union – which has been the focus of recent corruption and organised crime claims – said the royal commission would be a smokescreen for the government’s attack on wages and conditions.

Opposition Leader Bill Shorten said the commission would be a “lawyers’ picnic” and repeated calls for police to investigate the corruption claims.

“It doesn’t matter if you are an employer or a labour hire company or a motorcycle gang or a union rep, no one is above the law,” he told ABC radio.

“If you want to catch criminals, get behind the police.”

Parliamentary secretary Scott Ryan accused Mr Shorten of ignoring corruption in the unions.

A royal commission had powers to compel people to give evidence, he said.

“These are important tools to turn a light on dark corners of our society where we know that some practices are criminal,” Senator Ryan told Sky News.