Under the final terms of the land swap deal, the club was given three and a half years of rent-free tenancy on a block of land in Dickson that the club sold to the government, a block that currently houses the headquarters of the CFMEU.

It was one of several significant concessions the ACT's Auditor-General, Dr Maxine Cooper found earlier this year gave the club up to $2.6 million in value that was not part of an original tender the government issued to sell a carpark next to the Dickson club.

After two years of meetings between the club and the government, that deal was reached in December 2014, with scant public detail of what occurred during the talks.

While the government has paid the club $3.9 million for the block and a second one in Section 72, Dickson, the 42-month rent-free period for the union-controlled club, which sub leases the land to the CFMEU, expires at the end of the month.

Asked about the current status of the rent-free arrangement in ACT Legislative Assembly Estimates on Tuesday, Chief Minister Andrew Barr said the club was still in negotiations for "a short commercial extension" of the lease, the outcome of which "will probably be known in the next few days".

It is unclear what arrangements the club or union made for the future of the tenancy in the intervening three and a half years, and the club did not respond to enquiries on Tuesday.

A government spokeswoman said in a statement that the club approached the government for a short term tenancy while its new accommodation was being completed, and the club would remain on the site until September this year.

But the club, understood to sub-lease the site to the union and gym, would pay market rent for the three month period, while the extension was negotiated, though the government is still seeking two valuations to determine the rent amount.

The spokeswoman said the planning directorate had engaged a consultant to write and lodge a development application for the the demolition of the buildings on the site, Block 6, Section 72 Dickson, which would be lodged in "the coming weeks".

"Retaining tenancy over the next few months for the club and the [gym] will see business continue as usual, but also provide a level of security for the building while the development application is being assessed," she said.

Opposition leader Alistair Coe said the deal should be terminated and the fact the government was in talks to "see if another deal can be signed" showed the government had "absolutely no integrity".

"If the government does go into a new tenancy agreement with the CFMEU-backed Tradies, the negotiation should include recovering the $2.65 million owed to taxpayers," he said.