Wellington - New Zealand has approved trials of pig cell transplants to patients with Type 1 diabetes in revolutionary research that brings hope of a normal life to 30 million sufferers in the western world.

The first eight patients will receive the pancreatic pig cells at Middlemore Hospital, Auckland, early next year and if successful, the treatment could be licensed for general use within three years.

The transfer of live animal cells to humans - known as xenotransplantation - is highly controversial. Initial trials in Auckland in 1996 were aborted amid fears that pig viruses could infect humans and Australia introduced a five-year moratorium on the process in 2005 on grounds that its safety had not been proved.

After long consideration, New Zealand Health Minister David Cunliffe approved a clinical trial on October 21, 18 months after his ministry's Medicines and Medical Devices Safety Authority (Medsafe) cleared the process.

Type 1 diabetes is an auto-immune disease which usually strikes in childhood, destroying cells in the pancreas that produce insulin, a necessary hormone. Victims are then dependent on injections of synthetic insulin for the rest of their lives and often face complications, including blindness and the need to amputate affected limbs.

The treatment involves taking insulin-producing cells from the pancreas of newly-born piglets, coating them with a gel made from seaweed to give protection from the human immune system and inserting them into the patient's abdomen.

But they are no ordinary pigs. The animals being used are descendants of European pigs that were abandoned on the sub-Antarctic Auckland Islands, more than 300 kilometres south of New Zealand and now uninhabited. The pigs are disease-free, having lived in isolation for more than 200 years.

Living Cell Technologies, the company that will conduct the trial, is building a piggery near Invercargill, at the foot of New Zealand's South Island, to breed the piglets it will require under strictly controlled sterile conditions.

The treatment has been trialled in Russia where six patients who underwent the operation in June 2007 were able to cut their insulin doses by an average of 25 per cent and improved the control of their blood-glucose levels, Professor Bob Elliott, medical director of Living Cell Technologies, told the New Zealand Herald.

David Collinson, a director who helped found the company 20 years ago after his son was diagnosed with Type 1 diabetes, said one of the Russian patients was able to live without insulin injections for five months.

Elliott said the trials would progressively increase the number of pig cells transplanted to establish the optimum dose.

Opponents of genetic engineering, animal protection campaigners and Professor Patrick Manning, president of New Zealand's Society for the Study of Diabetes, have criticised the government's approval of trials.

Manning said the technique should be proven to work on animals before human trials started. "There's no doubt it will be a major breakthrough if successful, but we have to be very careful about the benefits and risks, which are as yet unknowable," he said.

But the National Health Committee, which studied the issue before reporting to Cunliffe, said the risk of infection to humans was considered low.

And Cunliffe said, "I had to balance the high probability of doing significant good for a number of people, if it was successful against the low possibility of doing great harm to the general population if it resulted in the spread of porcine retrovirus."

Australia's national ABC Radio reported that hundreds of Australians with Type 1 diabetes were trying to join the clinical trial in New Zealand and Elliott said Living Cell Technologies was keen to conduct similar trials there when the moratorium on xenotransplantation was lifted.