US President Joe Biden on Wednesday called for a deeper investigation into the origins of the coronavirus pandemic. 

In a statement, Biden said the majority of the US intelligence community had "coalesced" around two likely scenarios: that the virus was transmitted to humans via contact with an infected animal, or it emerged from a lab accident.

Biden said there was not "sufficient information to assess one to be more likely than the other."

He added that two of 18 intelligence agencies lean toward the animal link and one toward the lab idea, "each with low or moderate confidence."

Biden said US national laboratories should assist with the investigation and called on China to cooperate with the international probes. He expected results within 90 days.

"The United States will also keep working with like-minded partners around the world to press China to participate in a full, transparent, evidence-based international investigation and to provide access to all relevant data and evidence," Biden said.

US adviser Fauci doubts lab theory

Some Biden administration officials have harbored strong doubts about the lab leak theory.

Dr. Anthony Fauci, the White House chief medical adviser, said Wednesday that he and other scientists "believe that the most likely scenario is that this was a natural occurrence, but no one knows that 100% for sure."

"I believe we do need the kind of investigation where there's open transparency and for all the information that's available, to be made available and to scrutinize," Fauci said at a Senate hearing.

Andy Slavitt, Biden's senior coronavirus adviser, said Tuesday: "We need a completely transparent process from China. We need the WHO (World Health Organization) to assist in that matter. We don't feel like we have that now."

Biden's announcement comes after recent reports said some researchers at a virology lab in Wuhan, where the pandemic is suspected to have started in December 2019, were ill one month earlier.

China rejects lab-leak theory, slams US 'motives'

China wholly rejects the theory that SARS-CoV-2 escaped from a lab, and the Chinese Embassy in the US called the idea a "conspiracy theory" in statement released shortly after Biden's announcement. 

The embassy added that " some people are turning to their old playbook" and indulging in "irresponsible behaviors"

On Thursday, a Chinese Foreign Ministry spokesperson said the Biden administration's "motives were clear."

"The dark history of the US intelligence community has long been known to the world," the spokesman said, alluding to Washington's allegations of weapons of mass destruction in Iraq after September 11. 

The Chinese government has said the politicization of tracing the origin of coronavirus would "seriously hamper international cooperation on the pandemic."

Beijing says it supports a "comprehensive" study into early cases of the coronavirus.

WHO investigation inconclusive 

The WHO launched its own investigation earlier this year, but could not determine the animal source.

There have been concerns that China was not as cooperative with the investigation as they could have been.

However, the team determined that a lab leak was "extremely unlikely."

The virus has since spread to virtually every country around the world, killing more than 3 million people, according to Johns Hopkins University.

wmr,kbd,wd/msh (AP, Reuters)