Now is the time to speak, CFMEU whistleblowers told

The division has been accused of taking kickbacks, being linked to organised crime and employing standover tactics on worksites, according to a series of Nine newspaper reports.

"This behaviour has no place in Australia and I urge employers and workers who have suffered from CFMEU thuggery to speak out," Nationals senator Susan McDonald told AAP.

Federal Labor became the latest to cut ties with the embattled union on Thursday, indefinitely suspending affiliation between the construction division and the NSW, Victorian, South Australian and Tasmanian branches of the party.

It will not accept political donations or fees from the division in line with announcements from some state counterparts.

Labor senator Tim Ayres, who sits on the national executive, defended not suspending other states and territories, including Queensland, saying they responded to requests received from certain states.

"We have seen very clearly requests from premiers in those states," he told ABC TV.

However, Senator McDonald said the CFMEU had "perpetrated a culture of fear in the Queensland construction sector".

"I've spoken privately to individual workers and company heads who outlined the intimidatory tactics and outrageous demands by union heavies but they didn't want to go public in case they missed out on future work," the Queensland senator said.

"Some examples include dictating that only CFMEU members can perform certain tasks and stopping concrete pours halfway through the job to increase pressure on employers to fall into line."

Unionists also doorknocked embassies and told them to warn their citizens they would be exploited on Australian farms when the previous coalition government tried to bring in more foreign labour for farms, Senator McDonald said.

Independent MP Dai Le said she had also heard of standover tactics being used in her Western Sydney community, with people from non-English speaking background being forced to sign up and become members. 

"There's a lot of threats that I have heard of in the construction industry that happens out here in south-western Sydney," she told ABC TV.

"They were too scared to raise it because they said there were obviously people who were a part of the colourful bikie gangs."

Workplace Relations Minister Tony Burke announced the federal government would back a push for an independent administrator to take over the branch and referred allegations of criminal conduct to federal police. 

The Australian Council of Trade Unions, the nation's peak union body, has also suspended affiliation with the CFMEU's construction division.

But Opposition Leader Peter Dutton has called for the government to take stronger action and deregister the union. 

Deregistration would still allow the union to operate but with less regulation, Prime Minister Anthony Albanese said.

Griffith University law professor John Flood also called the move unnecessary, saying it would hurt workers by scrapping enterprise agreements negotiated with contractors and companies over the years.

The CFMEU's Queensland and Northern Territory branch secretary Michael Ravbar called the government's action overreach, saying the allegations in the media were unproven.

Australian Associated Press