The proposal from the Foy Group prompted 65 submissions, many highly critical of the environmental work done by Foy and many fiercely opposed to the project.

The Greens' Shane Rattenbury suggested this week that Foy could be trying "to dress up dirty processes" as green technology.

The ACT government sold the Hume land to Foy by tender in August 2016 for $3.108 million. It is unclear what happens to the land if the proposal is knocked back and managing director Stuart Clark said the sale deal contained no contingency arrangement to sell the land back to the government.

He was confident the project would be approved.

"We're confident that the environmental impacts are all positive. I'm sure that once we go through this process will achieve approval in due course," he said, describing Mr Rattenbury's intervention as misinformed and inflammatory.

"We're not trying to sneak anything though and we're not trying to trick anybody, it's a good thing," he said.

Planning Minister Mick Gentleman has now asked environment and planning acting director-general Gary Rake to appoint a panel of experts to start work this month. Mr Rake would seek advice from the ACT chief health officer in choosing members.

The panel would "thoroughly assess any potential impacts from the proposal", Mr Gentleman said.

"There is still a level of uncertainty on the extent of the impacts associated with the proposal, particularly in relation to public health impacts, as well as risks associated with the proposed technology," he said.

Foy wants to convert 200 tonnes of plastic a day into diesel and petrol, with the capacity to produce 70 million litres of fuel a year.

Mr Gentleman said the panel would research "comparable developments in close proximity to residents in other cities around Australia and overseas as well as the suitability of the Hume site for the proposed facility, particularly in relation to any long-term health impacts to nearby residents and any impacts on the future use of surrounding land".

"The ACT government is committed to diversifying our economy and attracting new businesses which improve our waste management, but we also need to ensure we appropriately assess new proposals and technologies," he said.

A public hearing would be held.

The panel would report by the end of April.

Foy has submitted a revised environmental impact statement, but it is yet to be released by the government.

Among submissions on the first environmental impact statement, neighbouring landowner Canberra Estates Consortium said the proposal did not consider future residential development at south Tralee and south Jerrabomberra, was presented as a waste recycling operation but could be better considered as a petrochemical manufacturing plant using mixed plastics rather than crude oil.

Mr Rattenbury said the Greens were concerned about the environmental impact of pollution from the factory, and its proximity to residents in the eastern Tuggeranong suburbs of Fadden, Macarthur, Chisholm and Gilmore.

He was also concerned about "why the Foy Group's proposal was not approved in NSW where it was initially proposed".

He did not have any further information on the NSW application, but Foy has a second project in planning in Berkeley Vale on the Central Coast. In information to the Australian Stock Exchange, Foy says NSW authorities want data from a plant in a like jurisdiction before they will approve the Berkeley Vale plant. The ACT factory is envisaged to provide that baseline data.

Mr Clark said the company's focus for now was on Canberra. "We're hoping to get that off the ground first then circle back round to NSW," he said. "We're hoping [Canberra] will be our showpiece as we go forward."

He welcomed the expert panel's investigation.

"The panel can review it and then can share the level of confidence that we have regarding the impact on the environment," he said. "There's a number of parties out there that need to be satisfied the project is safe ... The government is doing what they need to do, they need to make sure the plan is safe. And it is. And they need to appoint anyone they choose to to satisfy themselves. We're looking forward to the exercise."