More than 50 years after the United States ended nuclear testing in the Marshall Islands, test-affected islanders "feel like nomads in their own country", a UN special rapporteur said Friday.

Calin Georgescu said the governments of both the Marshall Islands and the United States "bear the responsibility to find effective redress" for islanders affected by Cold War period weapons testing.

The United States tested 67 nuclear weapons at Bikini and Enewetak from 1946-1958.

Georgescu, who has been on a four-day fact-finding mission to the Marshall Islands, will file a report to the UN Human Rights Council in September.

The US ambassador to the Marshall Islands, Martha Campbell, said earlier this month a $150 million nuclear test compensation agreement approved in the 1980s was "full and final" compensation.

She added the United States remains engaged in providing medical treatment to islanders exposed to fallout, and monitoring the environment in the affected islands.

Georgescu said the nuclear legacy is not resolved.

"I have listened to the concerns and stories of affected communities from Bikini, Enewetak, Rongelap and Utrik," he said.

"As a result of the nuclear testing, all of these communities have suffered dislocation, in one form or another, from their indigenous way of life.

"Many have become internally displaced persons who are yet to find durable solutions and expressed that they feel like 'nomads' in their own country."

Georgescu also noted many islanders "have suffered long-term health effects" from the nuclear testing, which was conducted while the Marshall Islands was a UN Trust Territory administered by the United States.

Marshall Islands Foreign Minister Phillip Muller expected Georgescu's report to give momentum to appeals to the United States for additional compensation, medical treatment programs and a clean up of nuclear affected islands.

"We hope it will help us gain international support for what we have been saying all of these years. We want the United States to step up to the plate to bring closure to the issue," he said.