Cougar Energy has been ordered to shut down its trial...

Cougar Energy has been ordered to shut down its trial underground coal gasification plant near Kingaroy in southeast Queensland.

The Department of Environment and Resource Management on Thursday told the company that no further coal gasification would be permitted at the site.

It makes final a decision to suspend the trial in July last year, when traces of the cancer-causing chemical benzene was found in groundwater monitoring bores on the site.

The department's acting director-general Terry Wall said Cougar must now remove all infrastructure from the site, unless agreed otherwise by the landowner.

"It also means Cougar must treat and dispose of any contaminated water in surface storages and clean up groundwater at the site," Mr Wall said.

"Cougar is required to continue groundwater sampling until the department is satisfied that rehabilitation has been completed."

The department would also do its own sampling to ensure Cougar complied with the requirements.

Last week, the department charged Cougar Energy with breaking the conditions of its environmental approval.

The department's monitoring program has not detected contaminants outside the Cougar Energy site.

? 2011 AAP