Union officials' access to work sites in Queensland will be restricted under changes to the Work Health and Safety Act.
Attorney-General Jarrod Bleijie introduced amendments on Thursday to force unions to provide at least 24 hours written notice before entering a work site.
Fines dished out to employers who breach electrical safety regulations will also be upped to $33,000.
Mr Bleijie says unions are exploiting work health and safety laws to hold projects and employers to ransom.
They enter workplaces using the excuse that there have been breaches, but the majority of times there are no immediate or imminent risks, parliament was told.
Mr Bleijie gave the example of one contractor which missed out on 42 days of work due to illegal strike activity in the first year of their Enterprise Bargaining Agreement.
Amendments to the act would stop unions bringing constructions sites to a halt, Mr Bleijie said.
"Quite frankly, their abuses of the current right of entry provisions are designed to bully contractors until they get their way," he said.
"Sites are being hijacked and workers held to ransom.
"For too long, we have seen construction unions using safety as an industrial weapon in this state."
"And hopefully we will rid this state of union militant bully activities."
Queensland Council of Unions president John Battams says while most employers do the right thing, some could exploit the changes.
"There are disreputable employers who will use the 24 hour notice period to try to cover up dangerous health and safety issues," Mr Battams told AAP.
"If there are health and safety issues they need to be dealt with immediately.
"This loophole created by the LNP government will be exploited by those companies who don't regard health and safety as the most important issue in the workplace."
The legislation has been sent to a committee for further scrutiny.
