The United States detonated 67 nuclear bombs in Marshall Islands between 1946 and 1958, and the health and environmental impacts are still felt today in the Pacific Ocean country, which is home to 42,000 people.

At the time of some of the tests, Washington was the UN's administering authority for Marshall Islands, with Heine charging it was "the only time in which any UN organ has ever explicitly authorized the detonation of nuclear weapons."

"We can't undo the past. But as a United Nations, we owe it to ourselves to make amends through the adoption of a resolution which formally apologizes for the failure to heed the petition of the Marshallese people," she said in a speech to the UN Wednesday.

Residents of the chain of islands and atolls had petitioned against the UN Trusteeship Resolutions that led to the territories falling under US control, she said.

The US State Department says that in 1947, the UN assigned the United States "administering authority over the Trust Territory of the Pacific Islands," which included Marshall Islands.

Washington says it has given more than $1 billion at current rates "to the affected communities."

- 'Deep scars' -

Heine said the tests had left an "ongoing legacy of death, illness and contamination. The impacts are handed down, generation to generation."

Thousands of Marshall Islanders were engulfed in a radioactive fallout cloud following the 1954 Castle Bravo nuclear test by the US military, and many subsequently experienced health problems.

Heine said Thursday the exposure was the "equivalent of 1.6 Hiroshima shots, every day, for 12 years."

Tonnes of contaminated debris from the testing was dumped in a crater on the Enewetak Atoll and capped with concrete that has since cracked, sparking health concerns.

Hundreds of islanders from the Marshalls' Bikini, Enewetak, Rongelap and Utrik atolls have also had to relocate due to nuclear contamination. Many are still unable to return home.

"Testing impacts left behind deep scars, with communities remaining in exile from their home islands, billions of dollars in unmet adjudicated claims, and a social and environmental burden upon our youngest and future generations," she said from the General Assembly rostrum.

"We did not choose this nuclear fate -- it was chosen for us."

A study issued by the US National Cancer Institute in 2004 estimated around 530 cancer cases had been caused by the nuclear testing.