The Ministry of Defence in Britain is rejecting a compensation claim by hundreds of New Zealand, British and Fijian veterans of nuclear tests in the Pacific - though it acknowledges it owes them a debt of gratitude.
More than 800 veterans are demanding millions of dollars in compensation from the Defence Ministry.
The veterans claim they were used as guinea pigs by the British government so it could study the effects of radiation fallout from the tests in Australia and the South Pacific between 1952 and 1958.
New Zealanders were among those who watched a series of nuclear explosions at Christmas Island in 1957 and 1958.
Many veterans have suffered a range of illnesses, from cancer to fertility problems and reduced life expectancy, which they blame on the dangerous exposure to high levels of radiation.
On the second day of a three-week court hearing in London, the government responded to assertions the veterans became ill as a result of radiation exposure from the tests.
Opening the ministry's defence, Charles Gibson, QC, acknowledged it owed the servicemen a debt of gratitude for their participation.
However, he said, lawyers for the claimants had misconstrued the law.
Central to the claim is a study from New Zealand's Massey University that links radiation exposure to genetic damage.
Mr Gibson said the evidence did not come remotely close to proving that the veterans' exposure to radiation led to their ill-health.
The court also heard that the action could not proceed because it was launched outside the legal time limit - which is three years after the event.
Several veterans are expected to be cross-examined during the three-week hearing.
