Colliers International ACT won the $654,500 asbestos taskforce contract in July to sell the suburban blocks, at an average price some industry insiders say could result in a loss for the firm.

The firm has faced heightened scrutiny since an audit of former Land Development Agency deals last year found it did unpaid work for the agency and a senior staffer engaged in "informal mentoring" of LDA staff.

Under the 12-month panel contract, Colliers is marketing and selling the properties, with the government covering marketing costs separately.

The contract covers sales of former Mr Fluffy blocks across the city since late July this year, replacing what were previously separate contracts for north and south Canberra awarded to Independent Property Group and Ray White, respectively.

Colliers' successful offer amounts, on average, to a $1636 per sales commission, not including marketing costs that are separately invoiced and are not listed in public documents.

While that figure is similar to the $1500 per block under one recent sale-only contract, it is significantly lower than the $7500 a block insiders say is an average figure for such commissions - a figure that would include marketing.

Other recent contracts show commissions for similar blocks vary between one per cent and 1.5 per cent of the final sales price; while the Colliers' commission would amount to an average cost of 0.32 per cent, based on an average block sale price of $500,000.

An asbestos taskforce spokeswoman said the price was a "lower agent fee per block", but that Colliers had tendered an "incentivised pricing model" that represented "the best value for money for the territory".

"The commission fee payable by the territory is proportionate to the volume of sales achieved under the contract, meaning the fee payable per block decreases as the volume of blocks sold increases," she said.

Colliers sales and marketing director Shane Radnell said the fee was "in line with current market rates offered for the sale of residential land" by the government and that marketing costs would be "borne by the government".

But three senior industry sources, including competitors, believe the low price potentially amounted to "undercutting the market" and may have led to low auction clearance rates.

"I can't see how they can do it for that, but I've since heard Colliers wanted to rebuild some credibility after the auditor-general's report and they were willing to take a loss on this contract," one said.

"It appears on face value that they've been brought before a committee to answer certain questions [about the audit].

"That put them in a position where they weren't able to win a contract and had to buy a job."

The taskforce spokeswoman confirmed only 37 per cent of properties offered sold at the first auction under the contract in October.

But she said such rates can vary greatly between auctions, citing two others in August with clearance rates of 41 and 71 per cent respectively.

"It is difficult to compare auctions as the number of properties and the location of the blocks varies,' she said.

"Certain mixes of available blocks will result in a higher clearance rate than others."

Mr Radnell said the firm had since sold 17 more blocks over the counter which were passed in at the October auction and that number was "increasing daily".

Schedules attached to the contract also show tenderers were meant to complete letterbox drops, hoardings and on-site signage as part of their "roles and responsibilities".

But the final schedules show Colliers was not contractually obliged to fulfil those parts of the tender, instead only being asked to consider such issues "as part of its marketing mix".

"As long as blocks are selling steadily the ACT Government will take advice from Colliers, however note that Colliers will 'do whatever it takes' to sell blocks," the documents read.

Mr Radnell did not explain why that clause was included, but said that Colliers would supply their own signage and the government would pay for letterbox drops and hoardings "if required".

The taskforce spokeswoman said the final contract provided "flexibility" to sell the blocks.

"The contract provides flexibility in approach to the sales program in order to allow Colliers to review performance and introduce different strategies to achieve the sales results – essentially doing 'whatever it takes' to sell blocks," she said.