CFMEU Victorian secretary John Setka and his deputy Shaun Reardon are facing blackmail charges as a result of the trade union royal commission.
The union confirmed this on Sunday as it criticised the way the men were arrested in front of their family and children.
"The CFMEU has cooperated with every request from the royal commission and the police could have conducted their business at the office during working hours," CFMEU construction division national secretary Dave Noonan said in a statement.
Related reading
Shorten in clear at unions commission
"The arrests were conducted in front of both families and reek of overkill."
Mr Noonan said both men would plead not guilty to the charges.
The pair were investigated by Taskforce Heracles, a joint Victorian and federal police unit that takes on cases referred from the Royal Commission into Trade Union Corruption and Governance.
In a statement on Sunday, Victoria Police said it had arrested a 51-year-old from West Footscray and a 47-year-old from Ocean Grove and charged each with one count of blackmail.
They were bailed to appear in the Melbourne Magistrates Court on Tuesday.
The charges are understood to relate to Boral and its supply of concrete to Grocon, a developer that has been the target of CFMEU industrial action.