Scientists from the Royal Society of Chemistry have warned the media over scaremongering over the Japanese nuclear crisis and advised the public around the world not to panic buy anti-radiation potassium iodide tablets.

The experts say that comparisons between the Fukushima nuclear power plant, where Japanese authorities are working to cool fuel ponds following last Friday's earthquake and tsunami, and the 1986 Chernobyl disaster are inaccurate.

One American drugs company has reported sales of 250,000 potassium iodide tablets as concern about radiation exposure spreads around the world, far in excess of the real dangers according to Dr Brian Carter, the environmental sciences programme manager at the RSC.

''It is highly unlikely that the situation in Japan will lead to a scenario where sufficient quantities of radioactive iodine, produced in a power station as a 3% fission product, are released into the atmosphere to cause a problem in the United States or anywhere else,'' Dr Carter said.

''For that to happen, huge quantities of iodine would need to be released into the atmosphere. The current situation is not of the same scale as the Chernobyl disaster.''

''For the US to be affected, an explosion would have to occur that was powerful enough for radioactive iodine to reach the upper atmosphere, get picked up by the jet stream then carried to the United States - a similar situation that occurred with the ash from the volcanic eruption in Iceland last year. It is possible that some radioactive iodine could make it to the US via this route, but it is unlikely that it would be at the level requiring extensive dosing using potassium iodide tablets.''

Dr Carter said that there was no shortage of supply of iodine worldwide, but inappropriate panic buying could affect supplies to those who really need it close to the exclusion zone in northern Japan.