At least 15 sites across the UK have been contaminated by radioactivity from second world war military hardware, according to new disclosures by the Ministry of Defence (MoD).

A dozen of the sites, which include current and former air and naval bases, have not been identified before by the MoD. Some are accessible to the public or are being developed for homes or businesses, though the potential risks are unclear.

The contamination comes from radium that was used to coat the dials of aircraft and other equipment so that they could be seen in the dark. It was in scrap burned and dumped in the 1940s and 1950s, and remains radioactive for thousands of years.

The contaminated sites include the old SAS headquarters at Stirling Lines in Hereford, a former naval air base near Portsmouth and a previous home to the Red Arrows in Gloucestershire.

The MoD has revealed the list of sites in response to a series of freedom of information requests in the wake of the discovery of dangerous levels of radium contamination at Dalgety Bay in Fife. It was home to a busy second world war air base.

In the past three months, 475 radioactive hotspots have been discovered on the foreshore near a public footpath and a popular sailing club. Several of the finds have been radioactive enough to cause skin burns, or to significantly increase cancer risks if swallowed.

The Scottish Environment Protection Agency is now trying to force the MoD to pay for Dalgety Bay to be cleaned up. It has threatened to formally designate the foreshore as Britain's first radioactively contaminated land.

But the MoD has so far been reluctant to make any commitment, partly because of the precedent it might set, experts say. Now it has revealed that there are a minimum of 12 previously unknown sites suffering "localised radium contaminated soil" due to "historical activities".

These are in addition to Dalgety Bay, and two other sites in Carlisle and Stirling that have been reported before. The MoD's Defence Infrastructure Organisation says that some of the sites have been, or are in the process of being, remediated.

"For the remainder the potential risk is being managed through the use of appropriate site controls in accordance with MoD policy," said an MoD spokesman.

Fred Dawson, who worked for the MoD for 31 years before he left as head of the radiation protection policy team in 2009, said the MoD had a "far from complete understanding of the extent and significance of radium contamination on the defence estate."

The issue had dropped down the MoD's agenda because of budget cuts, he argued. "This is in part due to the resources needed to go through old files, and the fear of what liabilities might be thrown up."

Contaminated sites

1. Sites not previously known to have been contaminated with radium:

HMS Daedalus, near Portsmouth: former naval air base

Defence Aviation Repair Agency Gosport, Hampshire: former aircraft repair depot

RAF Henlow, Bedfordshire: air base

RAF Newton, Nottingham: former air base

RAF Little Rissington, Gloucestershire: air base and former home to Red Arrows

Stirling Lines, Hereford: former SAS headquarters

RAF Shawbury, Shrewsbury, Shropshire: air training centre

RNAS Anthorn, Cumbria: former naval air base

RAF Machrihanish, Mull of Kintyre: former air base

Defence Aviation Repair Agency Almondbank, Perth and Kinross: former aircraft repair depot

RM Condor, Arbroath, Angus: Royal Marines base

RAF Kinloss, Forres, Morayshire: air base

2. Sites previously known to have been contaminated with radium

Dalgety Bay, Fife: a former world war two aircraft base

Forthside, Stirling: a former army luminising depot

RAF Carlisle, Cumbria: a former military equipment deport

source: Ministry of Defence