RAF Kinloss in Moray, already at centre of radiation investigation, could also be contaminated with sulphur mustard

A potentially unstable chemical weapon could be buried beneath an airbase that will shortly become home to more than 900 army personnel.

RAF Kinloss in Moray is already the focus of an investigation into radioactive contamination, and a report has emerged suggesting the site could also be contaminated with mustard gas.

Officially known as sulphur mustard, the colourless, oily liquid can cause severe burns and cancer when released.

A land-quality assessment uncovered by BBC Scotland identified potential sulphur mustard contamination in 2004 before construction work began on a pipeline for a water treatment project.

The report states: "Sulphur mustard is not a persistent chemical and under most conditions will readily break down. Under damp conditions (such as within soil) the action of hydrolysis can form an unreactive protective barrier around globules of active sulphur mustard. These globules can exist within the soil matrix and any disturbance to such a soil may puncture the globule and release the active sulphur mustard."

RAF Kinloss stopped functioning as an operational airbase last year after 72 years of service, as part of the government's strategic defence and security review.

About 930 personnel from 39 engineer regiment (air support) are due to move from Waterbeach, Cambridge, to Kinloss in July, where they will provide engineer support to the Royal Air Force and the army.

A Ministry of Defence spokesman said: "Our investigations to date suggest there is no indication of significant risk to public health or the environment associated with the past storage or disposal of chemical weapon agents in the UK. Work undertaken indicates the sites are suitable for their current use, provided that any management systems, restrictions or procedures remain in place.

"We consider protection of human health and the environment to be very important, and if we identify threats to either we inform the regulatory authorities and public as soon as possible ensuring the necessary management measures are put in place."

Thomas Docherty MP, a member of the Commons defence select committee, said he had called on the government to make an urgent statement on the matter.

He told the BBC's Sunday Politics Scotland: "The MoD has had a culture over seven decades of not sharing information. There's an arrogance about the MoD that is not new, but it has to be tackled once and for all."

He added: "We need an urgent statement from the UK government that spells out exactly who knew what when, that says what is the actual independent scientific risk, when did they inform the Scottish regulators, when did they inform the local authorities, and when did they inform Scottish ministers? And that needs to be done as soon as practicable."

The Scottish environment secretary, Richard Lochhead, said: "I am deeply concerned by media reports that the MoD may have sold land contaminated with radioactive material to communities around RAF Kinloss. I understand that the MoD is conducting investigations into possible contamination at the site.

"The secretary of state for defence must ensure that this work is comprehensive, transparent and completed as soon as practically possible. Should the presence of radioactive contamination be confirmed I will press the MoD to work with the Scottish Environment Protection Agency (Sepa) and start remediation work as a matter of urgency."

He continued: "Understandably, these reports will cause anxiety in communities around RAF Kinloss. It is imperative the Ministry of Defence does all it can to reassure the public in Moray and across the rest of Scotland that any further relevant information will be disclosed in full."

The SNP's Westminster defence spokesman, Angus Robertson, MP for Moray, has called for a meeting with the defence secretary, Philip Hammond, to discuss reports of waste at the Kinloss base.

Robertson said: "Recent reports raise questions relating to potential dangers at the Kinloss base. Given reports of radioactive material at Dalgety Bay, it is important that we understand the situation at Kinloss. This is why I'm requesting a meeting with the defence secretary Philip Hammond. It is important that there is as much transparency as possible from the Ministry of Defence."

The Moray-based convenor of the Scottish Green party's Highlands and Islands branch, Fabio Villani, said: "The MoD should come clean and disclose its records about the disposal of potentially harmful materials at Kinloss, Balnageith and at other former airbases elsewhere in Scotland. This would pave the way for contaminated land to be managed to avoid risks to human and environmental health, and for uncontaminated land to be brought safely back into productive use."