China's government has ordered a halt to work by a medical team that claimed to have helped make the world's first gene-edited babies. Vice Minister of Science and Technology Xu Nanping told state broadcaster CCTV Thursday that his ministry is strongly opposed to the efforts that reportedly produced twin girls born earlier this month.

Xu called the team's actions illegal and unacceptable and said an investigation had been ordered.

Researcher He Jiankui claims to have altered the DNA of the twins to try to make them resistant to infection with the AIDS virus. Mainstream scientists have condemned the experiment, and universities and government groups are investigating.

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There is no independent confirmation of what He says he did. On Wednesday, he revealed another woman in his study is possibly pregnant.

In videos posted to YouTube this week, He claimed he successfully edited the genetic code of twin girls while they were embryos. He says he used the gene-editing tool called CRISPR to delete a gene that makes people vulnerable to HIV, the virus that causes AIDS. The embryos were then implanted into the mother who gave birth to Lulu and Nana a few weeks ago.

"I think we still need to understand the motivation for the study and what the process was for informed consent," said Jennifer Doudna, a co-inventor of the CRISPR gene-editing tool, who watched He speak.

He said Wednesday that all the couples involved in his study consented and directed people to his website, where he provided an example of the consent form, which described the study as an "AIDS vaccine development project." He said he recruited the couples from an "HIV AIDS volunteer group."

He said seven couples are involved in the study; all of the fathers are HIV positive and the mothers are HIV negative. Experts said some of the risks with this particular gene editing, is a high risk of contracting other viruses, such as West Nile.