Former prime minister Gordon Brown says he has seen new evidence of "disturbing" levels of radiation at a Fife beach where wartime military aircraft were incinerated.
Mr Brown, who is MP for Kirkcaldy and Cowdenbeath, is stepping up calls for an urgent clean-up operation at Dalgety Bay, where "significant" sources of radiation were discovered earlier this year.
He is meeting defence secretary Philip Hammond to hand over a dossier highlighting recent discoveries of radioactive particles which, Mr Brown says, show the risk is higher than previously thought.
Laboratory tests have found that some of the more abundant small particles have unexpectedly high levels of solubility, making them more dangerous if swallowed, according to Mr Brown's dossier.
He also says small particles have been discovered in much larger numbers than previously reported.
The contamination is thought to stem from residue of radium-coated instrument panels used on military aircraft which were incinerated and land-filled in the area at the end of the Second World War.
The Scottish Environment Protection Agency (Sepa) and the Defence Infrastructure Organisation (DIO) have agreed a plan to treat the bay, but Mr Brown says that in the light of his new evidence, the Ministry of Defence should step in.
He said: "The only long-term way of lifting the threat of designating Dalgety Bay as radiation contaminated is a clean-up programme.
"With this new evidence the Ministry should now act. I want a decision to fund a remedial action programme that will allay the fears of local residents.
"People in Dalgety Bay have been patient, but without a commitment from the ministry to fund the clean-up, their patience is being exhausted."
Radioactive material was first detected on the foreshore of Dalgety Bay in 1990. In October last year a lump of contaminated metal was found on the beach, prompting the closure of part of the foreshore.
Sepa and the DIO are due to announce details of their plan to deal with the radiation at a meeting of the Dalgety Bay Forum on Tuesday.