Authorities are investigating the insertion of a car bomb under the vehicle of an Xstrata senior executive at the firm's Tahmoor Colliery site in New South Wales.

The company suspects the incident is linked to its long time dispute with the mining union.

NSW authorities said security personnel disrupted the two men who purportedly installed the bomb, composed of fireworks, on the executive's pickup at his property at Mount Kembla on the morning of Sunday.

Police stated that the bomb was lit and could have set the vehicle off, but it was put off by one of the security personnel. The car is understood to be the property of Operations Manager Darren Nicholls, an administrator at the Tahmoor facility.

Xstrata Coal said the act was "cowardly and violent" and demanded for Construction Forestry Mining and Energy Union to denounce such actions.

"Acts of violence and threats to the personal safety of our people will not be tolerated and we will pursue every legal option in our response," Xstrata said in a statement.

"It appears the ongoing dispute between the CFMEU and Xstrata Coal regarding the establishment of a new enterprise agreement at Tahmoor has now escalated to a point that an individual or some individuals believe violence is an acceptable negotiating tactic."

Around 230 mine workers are on strike at the Tahmoor Colliery for over a week now due to a long-time ongoing dispute regarding a newly implemented enterprise agreement.

The mining and energy division of CFMEU has "unequivocally condemned" yesterday the purported threat to Mr. Nicholls's personal safety.

Wayne McAndrew, vice president of the union, has called for support and cooperation with the police investigations. He claimed that Xstrata was attempting to use the incident as an issue against them.

"Xstrata has pre-empted the police investigation by drawing conclusions that the incident is in some way connected to the industrial negotiations between the union and management at Tahmoor Colliery," he remarked.

"Xstrata management should immediately stop using the police investigation for its own industrial purpose."

The CFMEU union office at Lidcombe was firebombed last month as well, and investigations are still underway.

"We know the only way to deal with these matters is to call for public co-operation and allow the police to properly investigate the matter," Mr. McAndrew added.

A spokesman from Xstrata said the CFMEU had been on strike for a total of 1100 hours in the dispute's duration. Over the 18 months that passed, there had been numerous meetings between Xstrata and union officers, 60 meetings in total, with no resolution being agreed on.