Senior officials within the Victorian division of Australia’s biggest construction sector union could face up to 15 years in prison after being arrested over their alleged role in a major blackmail attempt in relation to sites across Melbourne’s booming apartment building market.

Police attached to the taskforce associated with the Royal Commission into Trade Union Governance and Corruption have arrested Construction, Forestry, Mining and Energy Union (Victoria Construction Division) Secretary John Setka while he was driving with his family in North Melbourne.

Assistant Secretary (Victoria Construction Division) Shaun Reardon was also arrested, also reportedly in front of his family.

The arrests relate to allegations that the union attempted to lock building products supplier Boral out of the lucrative Melbourne apartment after the latter refused to cease supplying concrete to the union’s bitter enemy in building giant Grocon.

According to the allegations, the plot began in April 2013, when Setka and Reardon met with Boral representatives Paul Dutton and Peter Head.

During the meeting, the union reps allegedly told the Boral managers that the union was attempting to cut off Grocon’s supply line, and would thus target Boral if demands to cease supplying concrete to Grocon were not met.

In a statement, Victoria Police confirmed that both men had been charged with one count each of blackmail, which carries maximum penalties of 15 years imprisonment under the Crimes Act.

Both men have been bailed to appear before Melbourne Magistrates’ Court on December 8. The allegations have not been proven in court.

CMFEU National Secretary (Construction Division) Dave Noonan slammed the manner in which the arrests were carried out.

Stressing that the union had fully cooperated with the Commission, Noonan questioned why the arrests could not have taken place during business hours rather than in front of the men’s families.

“500 Swanston St is the address of the Victorian branch of the union where both men work from about 7am every week day,” Noonan said in a statement. “I thought the police might be able to Google that, but apparently not.”

Noonan acknowledged the importance of the role played by police, but slammed the treatment given to the men as a disgraceful attempt to damage the union without any regard for its impact upon their families.

He confirmed that both men would plead not guilty.

“The community expects more of the police. We should be able to trust that our police are not doing the grunt work of a Government desperate to mount an attack on the working rights of people in this country,” Noonan said.

“The Federal Liberal Government has taken 57 police and assigned them to a taskforce whose only achievements to date include two theatrical raids whose legality is in doubt, the prolonged questioning and harassment of staff in their homes, the failed pursuit of Johnny Lomax without any evidence and now, the hyper-staged arrests of two senior officers of the union.”