High-activity radioactive sources have been uncovered at Dalgety Bay which the Scottish Environment Protection Agency says give cause for concern and may prompt designation.
SEPA had recently extended its long-running investigation and particle removal work on the beach contaminated with particles from incineration of radium dial carrying World War II aircraft to the headland to try to find the source of particles which continually repopulate the beach.
It has long been a candidate to become the UK's first designated radioactively contaminated site, but regulators have resisted this because of the regular particle removal work.
But, last weekend, SEPA scientists found the biggest source so far in an area of the foreshore.
"An initial reading of activity in one of these sources has given sufficient concern for SEPA to have asked Fife Council to restrict access to the area," said the Agency's chief executive Campbell Gemmell.
"On Wednesday, Fife Council cordoned off an area of the foreshore close to the public footpath and temporarily erected further warning signs. In the short term, SEPA will continue the current investigation and ensure the removal of any further sources detected."
The material has been removed and is being analysed and discussions are underway with the Health Protection Agency and NHS Fife.
"It is now urgent that an appropriate long term remediation plan is developed, and SEPA will meet with Scottish Government and the Ministry of Defence to expedite this," said Dr Gemmell.
"This may require SEPA to designate an area of the foreshore at Dalgety Bay as radioactive contaminated land."
Principal policy officer in SEPA's radioactive substances team Paul Dale was quoted as having told BBC Scotland that when a detector had given a reading and sand was moved away to see if it strengthened, "it gave me cause for concern because it went off the scale".
Dr Dale said the area was covered with bricks and a team in protective gear removed the material in a shielded container.
He described the lump as looking like melted metal.
Environment secretary Richard Lochhead was quoted as saying he would write to the defence secretary urging action.
