Politicians have called on U.S. President Joe Biden to pressure China over its handling of the Covid-19 crisis in the face of mounting calls for a deeper probe of the theory that the virus may have originated through a lab accident in Wuhan.

During a news conference at the close of the Group of Seven summit, Biden was asked what he thought China must do to loosen tensions.

"I think China has to start to act more responsibly in terms of international norms on human rights and transparency," The Washington Examiner quoted Biden as saying.

"We haven't had access to the laboratories to determine whether or not...this was a consequence of the marketplace, of a bat interfacing with animals in the environment that caused this COVID-19, or whether it was an experiment gone awry in a laboratory," Biden said.

Last month, Biden said intelligence officials "coalesced" around theories Covid-19 originated through a lab accident or through human contact with infected animals.

Biden made clear that he remained dubious about China's cooperation with the World Health Organization inquiry. 

He directed U.S. intelligence officials to amplify their investigation into the origins of the virus and report back in 90 days, reports said. 

China has claimed the Biden administration was "playing politics" and "shirking its responsibility" by calling for a reinvestigation into the origins of the pandemic.

China's Foreign Ministry representative Zhao Lijian said Biden's directive shows the U.S. "doesn't care about facts and truth, nor is it interested in serious scientific origin tracing," The Organization for World Peace quoted the official as saying.

According to the WHO-China report, a lab leak was "extremely unlikely" and that a jump from animals to humans was most likely.

World Health Organization Director-General Tedros Adhanom Ghebreyesus said the lab leak "conspiracy theory" still needed further study, the Examiner said.