An Australian energy firm has been accused of hiding plans to use the controversial technique of fracking to exploit shale gas under central Scotland.

Dart Energy has insisted that it has "no plans" to mine shale gas in Scotland. But in a submission to the Australian Stock Exchange, it highlighted two major shale fields near Falkirk containing more than two trillion cubic feet of gas as "prospective" developments. The company also has an agreement with UK gas group BG for the rights to one of the shale fields, and has been promoting its Scottish shale gas assets to potential investors.

Shale gas is trapped in rock formations deep underground. It is freed by pumping in liquids under high pressure to fracture the rock, a process known as fracking. Fracking has been blamed for causing earthquakes, and contaminating water supplies with toxic chemicals.

Dart has applied for planning permission to sink 22 wells at 14 sites at Airth, near Falkirk to extract another type of underground gas, known as coalbed methane. But it has tried to distance itself from fracking and insists it isn't planning to exploit shale gas.

Critics allege that the company has either been misleading the public or its shareholders over its shale gas fracking plans.

Mary Church, campaigns co-ordinator with Friends of the Earth Scotland, said: "What it has said to the local community and what company reports say to shareholders simply can't both be true.

"In an effort to get the Airth coalbed methane project past the local community and planners, Dart is being extremely economical with the truth and hiding its real plans to exploit shale gas in the area."

Dart's coalbed methane applications have prompted more than 600 objections to Falkirk and Stirling councils, and were the target of protesters in Stirling yesterday. The applications are due to be considered in May at the earliest.

In a submission to the Australian Stock Exchange on May 10, 2012, Dart Energy included Black Metal Shale and Lothian (Broxburn) Shale in central Scotland as part of its "shale gas prospects" in Europe. The two fields were estimated to contain a total of 2.5 trillion cubic feet of shale gas. Dart's chief executive, John McGoldrick, was quoted as saying the company planned to develop the shale gas, as it had coalbed methane.

According to its 2012 annual report, Dart has a 100% interest in the gas rights to Black Metal Shale. Dart also operates the licence for the rights to Lothian (Broxburn) Shale, although it shares ownership with the BG Group.

Dart was accused of a "lack of transparency" by Scottish Labour's environment spokeswoman, Claire Baker MSP. She said: "We need leadership from the Scottish Government and a robust regulatory regime, or else we run the risk of fracking coming in under the radar."

Mark Ruskell, a Stirling councillor and former Green MSP, said the company was using its plans for coalbed methane as a "political door wedge" to keep options open for fracking in the future.

Dart has always insisted its "focus of operations" in Scotland is the exploitation of coalbed methane. It has said it has "no plans" to exploit shale gas in central Scotland, or to use fracking to get at the methane.

The BG Group confirmed it had an agreement with Dart covering a shale gas field in Scotland. A BG spokesman said: "It is not part of our plan to develop it at this time."