REVELATIONS that an underground coal gas plant in Australia is facing prosecution for allegedly contaminating more than 300 square kilometres of farmland have sparked fears that the same could happen in Scotland.

The Queensland government has launched a £3 million criminal court action accusing a mining company of leaking toxic chemicals and potentially explosive gases into the soil, water and air from a facility at Chinchilla, west of Brisbane.

The charge sheet, seen by The National, says the contamination is “extensive and widespread” and that the harm caused is irreversible.

Use of the technique of burning coal underground to extract gas for commercial use, known as underground coal gasification (UCG), is now planned for the Firth of Forth and the Solway Firth. Campaigners fear it could be disastrous, and are stepping up their demands for UCG to be included in the Scottish Government’s fracking moratorium.

However, the firms proposing UCG in Scotland say their technology will be deeper and safer.

The Australian firm facing the contamination charges strongly denies them. The Queensland government has imposed a 314 sq km “caution zone” around experimental UCG plants operated by Linc Energy in Chinchilla between 1999 and 2013. Digging below two metres is banned because of risk of explosion and pollution.

The government has charged that Linc “caused serious environmental harm”. The adverse effects included releasing contaminants to the soil and atmosphere in concentrations “above the explosive limits” and “above prescribed health and environmental investigation limits”, it alleges.

The firm could face multi-million pound fines and senior executives could go to jail, according to Jon Black, a Queensland government environment official. “They wilfully and knowingly undertook the operation, and they knew this could lead to catastrophic events,” he said.

According to a leaked expert report, air injected under pressure into underground coal seams caused surrounding rock to fracture. When the coal was set alight, methane gas, carbon monoxide, hydrogen and hydrogen sulphide spread through the ground.

Four government investigators were taken to hospital with suspected gas poisoning after testing soil at the site in March. High levels of carbon monoxide were detected in the blood of one, who suffered prolonged nausea.

The UK Coal Authority has granted two company licences to investigate UCG in five areas around the Firth of Forth, and a sixth area in the Solway Firth. The campaign group Frack Off has drawn up maps showing the impact of 300sq km of contamination around them, including half of Edinburgh, Falkirk and large parts of Fife (see table and map, above right).

Flick Monk, a campaigner with Friends of the Earth Scotland, warned that the Australian UCG experiment showed “the potential for disaster”.

She added: “We’d have to be crazy to risk allowing anyone to try burning the coal beneath the Firth of Forth.

“The UCG enthusiasts in Scotland will no doubt try to tell us that everything is different in Queensland.”

Local campaign groups reiterated their calls for UCG developments to be banned as part of the Scottish Government’s moratorium on fracking and unconventional gas extraction. “Communities won’t understand why they aren’t being afforded the same protections as those threatened by other forms of unconventional gas,” said Juliana Muir from Our Forth in Portobello.

Audrey Egan from Frack Off Fife warned that UCG would threaten the fishing, agriculture, leisure and tourism industries around the Forth. “The same process that catastrophically failed in Australia is being proposed here,” she said.

Robert Gatliff, the director of energy and marine geoscience at the British Geological Survey in Edinburgh, accepted that there could be problems. “There are well-documented concerns about the potential environmental impacts of UCG, and careful analysis of the Australian study and other published research on overseas projects will be required ahead of any proposed development in the UK,” he said.

However, UCG companies insisted what had happened in Queensland could not happen here. Cluff Natural Resources, which has three licences in the Forth and is to apply to start test drilling off Kincardine next year, issued a detailed statement.

It accepted that widespread pollution could have been caused by the “failed UCG project” in Queensland. But it pointed out that official tests of drinking water, rivers and groundwater in June had not found any breaches of health guidelines.

The Queensland plant had been gasifying coal 120m-140m beneath the surface, but UK authorities have recommended it should only be done at a depth of 600m or more, the statement said. Cluff is planning to exploit coal seams at a depth of 1000m.

The operation proposed in Scotland would not involve the use of high-pressure air, making fracturing less likely, Cluff said, adding: “The rigorous site selection process and design of the company’s subsurface infrastructure ensures that the very specific operational issues which allegedly resulted in the contamination of soils around the Linc Energy site could not be replicated at the proposed Kincardine UCG site.”

Five Quarter, which has two licences in the Forth and one in the Solway and is backed by the UK’s largest private landowner, the Duke of Buccleuch, took a similar line.

“The setting, engineering and processes involved in activities in Australia are entirely different from those developed by our company,” said chief executive Dr Harry Bradbury.

Linc Energy has contested the charges made by the Queensland government. “Linc Energy strongly rejects the allegations that its UCG demonstration facility has caused serious environmental harm,” said a statement from the company.

“Linc Energy is firmly of the view that the department commenced these proceedings without sufficient scientific evidence and, based upon our detailed knowledge of the operations and environment at our demonstration facility, that the allegations were taken out of context and/or are simply incorrect.”

Linc further accused the government of wasting taxpayers’ money in what it described as a “monumental mishandling of Queensland’s strained financial resources”.

It argued that the most likely cause of the contamination was “naturally occurring sub-soil processes”.

The Scottish Government insisted that UCG development had to be consistent with environmental objectives.

“No planning applications for UCG have been submitted in Scotland,” said a spokesman.

“If any application were submitted, it would be subject to the same careful, rigorous and evidence-based approach that we are adopting for unconventional oil and gas.”