THE radioactive fallout from a major accident at Sellafield 50 years ago was underestimated, with scores more falling ill with cancer as a direct result than previously thought.

In 1957, a fire at the Windscale nuclear reactor in Cumbria -- which has since been renamed Sellafield -- led to a release of radioactive material that spread across the UK and Europe.

New research claims the incident generated twice as much radioactive material and caused dozens more cancers than was previously thought.

However the findings - which were made by analysing weather patterns - show Ireland was not at risk because the radioactive cloud was carried over mainland Europe.

But residents of Dundalk, Co Louth, which was the nearest Irish town, point out that people in the immediate area had higher instances of cancer than other regions. It has been claimed that a cluster of Down Syndrome births and cancer cases in the area were caused by radiation.

The cancer rate in the area was estimated to be more than 12pc above the national average.

Fergus O'Dowd, Fine Gael TD in Louth, said the new research shows that the nuclear industry cannot be trusted.

"Up until now we were repeatedly told we were overplaying our concerns (about cancer) but now it's clear we weren't," he said.

"I'd be very concerned about the lack of truthfulness, and we clearly haven't been told the full truth until now."

He also pointed to a leakage of highly radioactive nuclear fuel two years ago, warning that problems still exist at Sellafield. About 20 tonnes of uranium and plutonium -- enough to make 20 nuclear weapons -- dissolved in concentrated nitric acid, escaped through a cracked pipe into a huge stainless steel chamber which is too dangerous for humans to enter.

Deputy O'Dowd has called for the setting up of an independent body to oversee the plant to ensure another disaster doesn't happen.

The new research, which was published in the journal Atmospheric Environment, claims the radioactive cloud spread further than just Cumbria.

On October 10, 1957, a failure to properly control the temperature of graphite control rods within the reactor sparked a devastating fire, which caused radioactive contamination to spew into the atmosphere. The fire was eventually put out with water -- an act which could have caused an explosion -- but a radioactive cloud had already spread.

At the time of the accident the levels and spread of the radioactive materials was estimated, and measures were put in place to limit contamination.

The study by John Garland, formerly of the UK Atomic Energy Authority, and Richard Wakeford, a visiting professor at the University of Manchester, suggests the contamination of the environment may have been much higher.

The team carried out a re-analysis of data taken from environmental monitoring of air, grass and vegetation and combined this with computer models that revealed how the radioactive cloud would have spread from the reactor with the meteorological conditions at that time.

They confirmed radioactive iodine and caesium were released, as well as polonium and a very small amount of plutonium, but found that the levels would have been higher than previously thought.

This would have also impacted the numbers of cancers that the accident would have caused, said the authors. Previously, it was thought that the radiation would have eventually led to about 200 cases of cancer, but the new contamination figures suggest it could have caused about 240.

Prof Peter Mitchell, the author of another study, has also said the radioactive plume did not pass across Ireland.

Irish Met Office measurements in Dublin from the time of the Windscale fire gave no indication of any trace of the plume.

In the past the State's nuclear watchdog, the Radiological Protection Institute of Ireland (RPII), warned the plant will pose a major threat to Ireland for another 150 years