A South Korean scientist who claimed a string of extraordinary cloning successes resigned from his post today after a university panel found that his work had been faked.

Woo Suk Hwang was officially designated Korea's "Top Scientist" this summer after he claimed to have cloned a human embryo and a dog, and to have developed patient-specific stem cells, a potentially revolutionary treatment for diabetes and Parkinson's disease.

But last week, Dr Hwang was accused of fabricating his most recent claim - to have tailored 11 colonies of stem cells for individual patients.

Today, a panel appointed by Seoul National University said that at least nine of Dr Hwang's colonies had never existed. The authenticity of the two remaining colonies is yet to be established. The panel found that Dr Hwang had manipulated photographs and falsified data to support his findings.

Dr Hwang, who is 52 and had recently been treated in hospital for stress, immediately resigned.

"I sincerely apologize to the people for creating a shock and disappointment," he told reporters as he left his office at the South Korea's best known university. "With an apologetic heart... I step down as professor."

Despite his resignation, Dr Hwang maintained today that his experiment had been successful: "I emphasise that patient-specific stem cells belong to South Korea and you are going to see this," he said.

The subject of the university panel was a paper published by the journal, Science, in May, in which Dr Hwang claimed to have developed patient-specific stem cells by grafting nuclei from donated eggs to skin cells from patients who needed treatment.

Dr Hwang's work was celebrated as a staggering technical achievement and appeared to confirm his position as the world's leading stem cell scientist. His claim to have cloned a human embryo in February 2004 had originally launched him to fame and iconic status in South Korea.

The investigation, led by Roe Jung-hye, the university’s dean of research affairs, found that the data for the 11 stem colonies Dr Hwang claimed to have made were all derived from just two collections of stem cells.

"This kind of error is a grave act that damages the foundation of science," the panel said.

"Based on these facts, the data in the 2005 Science paper cannot be some error from a simple mistake, but can only be seen as a deliberate fabrication to make it look like 11 stem-cell lines using results from just two," the panel said.

"There is no way but that Professor Hwang has been involved," Roe told a news conference, adding that DNA tests were expected to reveal whether the remaining two stem-cell colonies had been successfully cloned.

Given the deliberate nature of the fraud, the panel said it would now investigate Dr Hwang’s other landmark discoveries, including his Science paper in 2004 describing the world's first cloned embryo and his claim, made in the journal, Nature, to have made Snuppy, the world's first cloned dog. Both journals are already reviewing the work.

Choi Seong Sik, the country's vice minister of science and technology, said the government, which has given Dr Hwang 40.5 billion won (£23 million) to pursue his work, was "miserable" at today's news, and would consider withdrawing his "Top Scientist" title. Earlier this year, the country commissioned stamps in Dr Hwang's honour, showing a man rising from a wheelchair to walk.

British scientists said that trust between scientists was of absolute importance, and that Dr Hwang might have falsified his results under pressure to maintain the velocity of his achievements and to justify his generous funding.

"This is very disappointing news. I guess we should have been suspicious, given the speed with which he overcame problems that were holding back other labs. I guess in the end the pressure to succeed was too great," said Professor Jack Price of the Institute of Psychiatry. "So much had been invested in him by the state. This is a spectacular collapse."

Dr Huseyin Mehmet, senior lecturer in neurobiology at Imperial College, London, said: "The integrity of scientists is of paramount importance in medical research. This sad outcome illustrates the pressure on scientists to publish their work and put findings into the clinic, sometimes prematurely."

Dr Hwang is a veterinarian who said he became fascinated by cloning because he wanted to make healthier cows.

Doubts about his methods and experiments started in early November, when a respected American collaborator, Dr Gerald Schatten of the University of Pittsburgh, ended his relationship with the scientist's new World Stem Cell Hub citing ''ethical violations'' over the procuring of eggs.

On November 24, Dr Hwang revealed that some of the human eggs used in his research came from his researchers, a breach of ethics that was criticised by colleagues.

Then, last week, Dr Schatten wrote to Science, asking that his name be removed from Dr Hwang's seminal article. Dr Schatten co-authored the paper without witnessing the experimental work that produced the stem cell colonies. According to The New York Times, Dr Schatten wrote that he had ''substantial doubts about the paper's accuracy'' and had heard that some of the experiments had been fabricated.

Dr Schatten's letter was followed by the revelation of Dr Hwang's former research partner, Dr Roh Sung-il, who told Korean television that Dr Hwang had admitted to him that nine of the 11 stem-cell lines had never existed.

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