The Japanese government-backed Riken institute said Tuesday it had found evidence of scientific misconduct including the falsification of images and plagiarism connected to portions of published regenerative stem cell research previously hailed as groundbreaking.

The prestigious, government-funded institute told a news conference in Tokyo that it had found key data to have been falsified in two papers published in the journal Nature in late January.

Riken's investigative panel said there was research misconduct on two points and stated that lead author, Haruko Obokata, had acted in a manner that was "inexcusable."

"(Doctor) Obokata acted in a manner that can by no means be permitted when she manipulated the image data of two different gels and using data from two different experiments."

"Given the poor quality of her laboratory notes it has become clearly evident that it will be extremely difficult for anyone else to accurately trace or understand her experiments," Riken's investigators said.

The institute is expected to insist that Obokata retracts the papers which were published in January and purport to show a new phenomenon, known as stimulus-triggered acquisition of pluripotency (STAP).

Obokata and her team, according to two papers published on the topic, tested a number of different conditions to ascertain if any could reset the polarity state of mouse lymphocytes taken from the spleens of young mice.

Obokata, in one of her team's studies, concluded that by moderately lowering the pH level of the cell culture for less than 30-minutes, the pluripotency gene became further expressed in a portion of the cells.

This, according to the study, showed that the cells had been transformed into an embryonic-like state and Obokata's findings were quickly heralded by the scientific and medical community as a quantum success because the new process means that no potentially dangerous genetic manipulation is needed, meaning the potential benefits of the STAP method for cancer research, next-generation pharmacology and regenerative medicine could be huge.

But while Obokata rejects the institutes' allegations that she knowingly falsified key data, the panel concluded the evidence they've found has "destroyed the credibility of the data from its foundations, and that she used the images while being fully aware of the risks".

Riken President Ryoji Noyori, the 2001 Nobel Prize winner in chemistry, said the institute will severely reprimand all of those involved in the case, including himself, and that the institute will work hard to prevent further instances of fraudulent research in the future.

Chief Cabinet Secretary Yoshihide Suga said Tuesday the panel's findings were "extremely regrettable," and urged Riken to " fully implement preventative measures."

Riken has also said it will spend up to a year if necessary studying the STAP cells findings, by trying to replicate them through lab tests, with Noyori saying the institute will cooperate with outside experts in the new research.

Obokata said through her lawyer she plans to appeal the panel's findings, stating that with regard to her entire findings being potentially spurned she "absolutely cannot accept such an implication."

Riken's investigative panel have yet to make it known whether Obokata's STAP cells actually exist or not.