The safety of a remote atoll dusted with fallout from United States hydrogen bomb tests in the Marshall Islands in the 1950s is being evaluated by independent scientists.

Ailuk Atoll, a tiny necklace of coral islands in the central Pacific Ocean that are home to about 400 people, is classified by US government agencies as not exposed to nuclear test fallout.

However, a US Department of Energy study documents that the atoll was exposed to levels of radioactivity significantly above internationally recognised exposure limits.

People living on Ailuk in 1954 received a similar level of fallout to nearby Utrik Atoll from the 15-megaton Bravo H-bomb test at Bikini, but were not similarly evacuated afterwards.

A presidential commission on human radiation experiments in 1995 concluded that Ailuk's population should have been evacuated.

Ailuk has never been included in any of the special medical or compensation programs afforded to the four atolls, including Utrik, which the US acknowledges were irradiated.

The current environmental radiological survey of Ailuk is being funded by the Nuclear Claims Tribunal, an agency established in Majuro to compensate islanders for exposure to the 67 US nuclear tests in the Marshall Islands.

The tribunal's Mr William Graham said because of Ailuk's position at the periphery of the fallout belt in the northern Marshalls, information from the survey was expected to shed light on whether other nearby atolls that received low- and medium-level doses of fallout in the 1950s needed similar follow-up environmental surveys.

Staff from a US firm took samples from 40 islands in Ailuk Atoll this month, which are now being analysed in Majuro. The survey would determine if any nuclear clean-up was needed, Mr Graham said.

A wide range of environmental samples was collected, including coconuts, pandanus, breadfruit, papaya and soil.

Chicken, pig and coconut crab samples are also being tested for radioactivity.

Last month the tribunal awarded Bikini islanders $US563 million ($1.1 billion) in compensation for the tests.

Agence France-Presse