Japanese scientists have determined that the force of tsunamis that devastated Thailand's resort town of Khao Lak two weeks ago was equal to as much as one-fifth of that of the 1945 atomic bombing of Hiroshima, it was reported on Monday.

A group of scientists came to the conclusion after studying the exteriors of buildings in the town that were hit by the December 26 tsunami, the Yomiuri Shimbun said.

The team estimated the pressure of the water currents at 3.7-6.7 tons per square meter, with the thrust of the Hiroshima bomb blast near ground zero put at 35 tons per square metre, the major daily said.

Led by Akita University assistant professor Hideo Matsutomi, the team also found that the height of the tsunamis ranged between 3.1 and 10.6 metres and their speed between six and eight metres per second.

Matsutomi was not immediately available to confirm the report.

In the popular resort of Phuket, some 50 kilometres south of Khao Lak, the pressure of tsunamis was far less at 0.9-1.6 tons per square metre, the report said.

Khao Lak, almost totally unknown to tourists just three years ago, lies in the worst hit province of Phang Nga, where thousands of people, many of them foreigners, were confirmed dead or missing in the tsunamis.

Hiroshima, a garrison town in western Japan, was on August 6, 1945 flattened by a US atomic bomb with a 60 kilogram core of uranium-235.

It exploded with a blast equivalent to 12 thousand tons of TNT, killing an estimated 140 000 instantly or by the end of that year