The nation’s leading building union has accused the Abbott government’s royal commission into trade unions of unjust treatment and a lack of procedural fairness, according to media reports.

News Ltd has reported that lawyers for the Construction, Forestry, Mining and Energy Union wrote to the Royal Commission for Trade Union Governance and Corruption on Friday suggesting that the Commission’s solicitors allegedly withheld crucial information such as the number and names or witnesses and the complete timetable of hearings until late last Friday.

According to the report, the Commission provided the union’s lawyers with a list of witnesses last week but continued to add new names up until Friday.

Describing the process as ‘unjust’ from a viewpoint of procedural fairness, Slater and Gordon head of Industrial and Employment Claims Phillip Pasfield reportedly wrote in the letter that timeframes provided were unrealistic and that the union could not guarantee appropriate responses within timeframes allowed.

“My clients of course will do their best to cooperative with the commission’s timetable but it is most unlikely that the timetable will be met,” Pasfield is quoted as saying in the letter.

The letter comes as the union prepares to undergo three weeks of public hearings commencing in Canberra commencing this week, during which 37 witnesses are expected to give evidence.

This follows earlier hearings in Sydney in which fourteen witnesses gave evidence last month as well as earlier hearings into practices at other unions including the Australian Workers’ Union, the Electrical Trades Union, the Trade Workers Union and the Communications, Electrical, Electronic, Energy, Information, Postal, Plumbing and Allied Services Union of Australia.

The hearings in Canberra follow a protest march on the offices of the CFMEU’s ACT branch last week during which a number of workers allegedly tore up their union membership and contractors complained of intimidation on work sites.

The union, in turn, called for an investigation into sham contracting, tax evasion and phoenix activity within the ACT’s formwork industry.

The Commission responded to the union’s complaints about time-frames by acknowledging the workload associated with the hearings but stressing it had given as much notice as possible and saying it did not see any issues with procedural fairness.