Christopher Rochester, 24, of Chester-le-Street, County Durham, died from internal bleeding after being left unattended on a hospital trolley while on holiday in Faliraki in June 2000.

When his body was flown home, a post-mortem examination found that a kidney was missing. An organ was later returned to the family, but tests on it failed to produce a genetic match.

Mr Rochester's mother, Pam Cummings, and stepfather George Cummings, fought a seven-year campaign to convict a Greek doctor of manslaughter by neglect.

The couple also campaigned for a separate investigation into the kidney mix-up, but they said that a letter from the Greek authorities had insisted the body be exhumed for fresh tests.

Mr Cummings said that while the Greek authorities had agreed to independent DNA tests in Belgium or France, they wanted new material from the body to be used instead of the DNA samples from a biopsy Mr Rochester had before his death.

Mr Cummings said his wife was "devastated" by the request and that the Greek authorities would "cause as much pain, grief and unhappiness as possible to the family".

But he said the family would give permission for the exhumation in order to properly complete the investigation. "They are hoping that we will say no, because if we said no, they would be able to close the case because we would not be co-operating with them," he said.

The family believe the organ mix-up may have been deliberate to cover up vital evidence about the true cause of Mr Rochester's death.

Mr Cummings added: "If we can be given Christopher's kidney and we can put it with him, we will feel that we can put him to rest."