A second scientific journal is investigating research by an embattled stem cell scientist — this time his claim that he cloned a dog.

Hwang Woo-suk, internationally renowned for stem cell breakthroughs, is at the center of several probes into his research claims, including two by scientific journals.

The announcement of an investigation into Hwang's dog cloning paper by the respected London-based journal, Nature, is merely the fallout of other allegations. The cloning report had drawn international headlines because dogs had not been cloned before.

In a statement this week, Nature said it has no information casting doubt on the paper, which reported in August that an Afghan hound named Snuppy was produced through cloning. But given allegations that Hwang faked results on other research, the journal said there is "sufficient uncertainty ... for us to wish to remove any doubts over the Nature paper."

Nature said its investigation probably won't be concluded before January.

Seoul National University, where Hwang works, was already looking into allegations that he faked the creation of 11 human stem cell lines that were genetically matched to individual patients.

A former colleague of Hwang's, Moon Shin-yong, told The Associated Press on Wednesday that he has asked the university to investigate an earlier paper, in which Hwang claims to have created the world's first cloned human embryos and extracted stem cells from them.

"In the scientific community, when one paper is proven to be fabricated, it is customary to review all related papers," Moon told AP by telephone. Moon, who was questioned by the university on Wednesday, added that he does not yet know of any problem with the article.

Hwang's cloned-embryo paper was published last year in the journal Science, which said on Tuesday that it was investigating that work.

At issue are two vital photographs that Hwang used to illustrate his breakthrough claim. They appear identical to photos of stem cells that appeared in 2003 in the journal Molecules and Cells in an article describing a routine experiment.

Hwang has admitted what he called "fatal errors" in this year's report about creating 11 lines of stem cells. He has asked Science to withdraw the paper, which it published in May. He acknowledged that at the time of publication, his team had created only eight cell lines. But he said three more were created later.

Hwang has maintained the research is genuine and said tests will show his team has the technology to produce the embryonic stem cells, which can be manipulated to grow into any body tissue. Scientists hope to use the technology to create transplant tissue for treating illnesses like diabetes and Parkinson's disease.

Hwang acknowledged the faults in the paper a day after co-author Roh Sung-il said that Hwang had pressured another scientist to fake data for the report. Roh, head of Seoul's Mizmedi Hospital, alleged nine of the 11 cell lines were faked and the authenticity of the other two was unknown.