The Cook Islands government is dismissing a claim some residents of the northern group may have been affected by British nuclear weapons testing on Christmas Island in the 1950s.
The British interior ministry, the Home Office, has failed to give a full response to a letter written by Tauariki Greig, who used to live on Rakahanga in the northern Cook Islands.
Mrs Greig says her mother and father were affected by the tests, and her own present illness stems from when she witnessed one explosion in 1957.
"We were playing hide and seek. Kids. And I was on my father's shoulders when it happened. I saw a flash, like lightning, and killed all the fish."
Mrs Greig says DNA testing in New Zealand points to genetic mutations as the cause of cancer-like symptoms.
She says she wants the Cook Islands to carry out a full study into the possible health effects of the tests, and for compensation to be awarded.
An official in the prime minister's office, Helen Wong, has dismissed the claims, suggesting Rakahanga is too far away from the test site to be affected.