Construction workers in Western Australia face having their assets seized for failing to pay fines for an unlawful strike.

It is the first time in Australian history this type of action is being taken.

More than 100 union members were fined more than $1 million last year for taking part in the eight day strike at Woodside's LNG project on the Burrup in 2008.

Subsequently, more than $300,000 of the fine was suspended and the workers were left to pay a total of $680,000.

Fair Work Building and Construction said 33 of the 117 workers from the AMWU and the CFMEU have failed to pay up.

Fair Work director Nigel Hadgkiss said those workers face having their assets seized.

"It's the first occasion we've had to resort to this kind of action," he said.

"For eight days there'd been unlawful industrial action and it had resulted in significant economic losses and project delays."

Mr Hadgkiss said Fair Work has moved to recover the funds owed.

"Those that haven't paid the fines, sufficient time has elapsed that we are giving instructions to move to recover what is owed," he said.

"We have to obviously identify the property and this is most commonly cars and houses.

"In order to do that, we filed and served what's called property search and seize orders, and the bailiff is currently executing those orders."

Mr Hadgkiss said it should serve as a warning to workers.

"If you break the law, you've got to be prepared to pay the consequences," he said.

"I hope it's a salutary lesson to all workers that if they breach workplace laws, then this agency will, quite frankly, not hesitate to enforce penalties that are imposed by judges and the courts."

Seizures designed to intimidate: unions

The CFMEU's state secretary Mick Buchan said the fines were designed to intimidate unions.

"I think it's appalling; the matter was resolved with their employer at the time," he said.

"It was some time later that the ABCC intervened and brought charges against individuals.

"Once the Abbott Government was introduced and Hadgkiss took over the ABCC, he went straight after the workers. It's out of control at the moment."

Mr Buchan says the union will support those affected.

"We are keeping in constant contact with our workers, we look after our own during these times," he said.

The union leader says the Abbott Government is sending a clear message to workers through Fair Work.

"I think they're trying to send a message of fear and intimidation," Mr Buchan said.

"We are finding on a lot of these jobs now, that workers are in a spot where they're reluctant to bring up safety issues. We're in a high risk industry and when that message comes out it can create pretty tense and dangerous situations on site."