U.S. officials are reportedly investigating an unverified theory pushed by conservatives including President Trump that the coronavirus outbreak began in a Chinese laboratory.

CNN reported Thursday that officials are probing numerous theories related to the origin of the coronavirus outbreak, including one that suggests poor lab safety protocols allowed a virus that may have originated at the lab to be carried out with personnel.

The theory, which has not yet been corroborated, is reportedly one of multiple possibilities the U.S. is investigating.

The latest developments come days after the chairman of the Joint Chiefs of Staff, Army Gen. Mark Milley, told reporters that the U.S. intelligence community was taking "a hard look" at the theory.

"I would just say, at this point, it's inconclusive, although the weight of evidence seems to indicate natural [origin]. But we don't know for certain," he said, referring to the likelihood that the virus originated naturally, rather than in a lab setting.

One White House source also appeared to dismiss the theory in a statement to CNN, telling the network, "[E]very time there is an outbreak someone proposes that the virus or other pathogen came out of a lab."

Trump told reporters at the White House on Wednesday that China "needs to come clean" about what it knows about the origins of the coronavirus.

U.S. officials and Capitol Hill Republicans have hammered the Chinese government and the World Health Organization over the handling of the early days of the outbreak, accusing Beijing of deliberately hiding information about the virus as well as accurate counts of its infected population from health experts.

The city of Wuhan, China, where the virus is believed to have originated, announced last week that it would continue testing residents for the virus despite reopening many businesses in the city and ending a lockdown.