Embattled cloning pioneer Hwang Woo-suk has asked prosecutors to investigate whether his patient-specific stem cells had been switched with ordinary stem cells.

In a petition filed with the Seoul Central District Prosecutor's Office Thursday, Hwang said the creation of tailored stem cells had been carried out smoothly at his lab in Seoul National University.

But he claimed that one of his former assistants, Kim Sun-jong, had made the switch and had fabricated Hwang’s research results in the course of playing a vital role in the process of stem cell production.

The prosecution, which has been cautious on the launching of a probe into the matter, is likely to begin investigations into the event should an SNU investigative panel announce significant findings about Hwang's research.

The cloning pioneer's latest move comes in the wake of MizMedi Hospital CEO Roh Sung-il’s claim that Hwang had created no stem cells at all.

Hwang has admitted to flaws made in a paper on stem cell research published in Science magazine this year, but has denied claims that he had failed to develop the core technology needed to create patient-specific stem cells.