Politicians and scientists from around the world have grown increasingly frustrated by China’s efforts to deflect an investigation into the origins of the coronavirus, especially the possibility that it leaked from a Wuhan laboratory.

The data, first submitted to the US-based Sequence Read Archive in March 2020, were “requested to be withdrawn” by the same researcher three months later in June, the US National Institutes of Health said in a statement Wednesday.

Details of the genetic makeup of some of the earliest samples of coronavirus in China were removed from an American database where they were initially stored at the request of Chinese researchers, US officials confirmed, adding to concerns over secrecy surrounding the outbreak and its origins.

The data, first submitted to the US-based Sequence Read Archive in March 2020, were “requested to be withdrawn” by the same researcher three months later in June, the US National Institutes of Health said in a statement Wednesday. The genetic sequences came from the Chinese city of Wuhan where the Covid-19 outbreak was initially concentrated.

The reason cited at the time for withdrawal was that the sequence information had been updated and was being submitted to another database, the agency said. The researcher asked that the data be removed “to avoid version control issues,” it said.

“Submitting investigators hold the rights to their data and can request withdrawal of the data,” the agency said. “NIH can’t speculate on motive beyond the investigator’s stated intentions.”