Mr Barr accused the federal Coalition government and ACT opposition of institutional memory loss over the memorandum of understanding signed with UnionsACT in March 2015, pointing to a 2009 committee hearing when Canberra Liberal's treasury spokesman Brendan Smyth discussed the document with union officials.

Opposition Leader Jeremy Hanson and federal Employment Minister Michaelia Cash both said the agreement amounted to a right of veto and a secret deal with trade unions. Both sought to link it to the powerful Construction, Forestry, Mining and Energy Union on Wednesday.

The first agreement was signed between unions and the ACT government in 2005, when the Howard government first introduced its controversial WorkChoices industrial relations laws.

Mr Barr suggested more-recent versions of the agreements were symbolic and required the territory to follow only existing laws related to procurement and union activities. Industry groups were welcome to propose their own similar agreements with the government, Mr Barr said.

"[Union leaders] provide advice, like members of the public can, and in fact like industry associations do," Mr Barr said.

"All government procurement is undertaken in accordance with the Government Procurement Act 2011, which requires value for money."

He said members of the community with a predisposition to anti-union views might see the agreement as favouring unions.

"This is a long-standing thing. It has been through three elections now," Mr Barr said. "Procurement issues generally aren't ones that excite people."

In the document the government agrees to provide UnionsACT with a list of firms tendering for work, before any contract is awarded. A fact sheet distributed by secretary Alex White said the agreement requires workers' rights and safety to be taken into consideration and the most recent version included recommendations from the 2015 inquiry into construction site deaths.

The agreement states it is designed to ensure proper consideration of workers' rights.

Agencies must decline to award tender proposals to firms that do not provide undertakings to comply with work safety laws, recognise trade unions as the representatives of workers and facilitate some union activities.

"This agreement reflects a desire on the part of the ACT government to strike a balance between ensuring an open process in the selection of tenderers to provide or perform works and services to (or on behalf of) government, with a firm commitment to meet the expectations of the community in implementing its procurement policy," the document says.

"The purpose of this agreement is to ensure ACT government procurement activity includes fair consideration of the rights of workers. Nothing in the [memorandum] is intended to oblige the ACT government to act in any way in breach of any law or trade agreement."

Mr Hanson said the agreement gave unions unfair and improper access to the tendering process.

"It seems to be almost contracting out the process to the unions, giving them extraordinary powers to access company records, to give the unions the list of companies tendering for government contracts.

"To give them such unfettered access and influence to the tendering process in this town is extraordinary".

Mr White said it required consultation on the industrial relations record of the firms tendering for government contracts.

"If there is a company ... that has been taken through the Fair Work Commission or the ACT Magistrates Court or another tribunal and they've got a record of ripping off workers or breaking some other kind of law, the memorandum of understanding gives us the right to inform the procurement officers in the various directorates."

Master Builders ACT executive director Kirk Coningham called for an end to the agreement.

"The ACT government must move to scrap the MoU and return the territory to a competitive commercial tender process," he said.

News of the document comes three months after former police minister Joy Burch resigned in the wake of allegations over her chief of staff's contact with CFMEU ACT secretary Dean Hall.

A police investigation into the incident has been under way for three months.