There is no evidence the coronavirus was engineered in a lab, according to scientists.
Conspiracy theories spreading online have claimed that the virus, which has claimed almost 1,400 lives in China, was made as a biological weapon and released by accident.
These were made stronger by the revelation that the Chinese government runs a secretive virus laboratory in Wuhan, the city at the centre of the outbreak.
But scientists who have studied the structure of the virus in detail say there is nothing about it which suggests it has been edited by humans or machines.
Its mutations appear to be natural evolution rather than any bizarre or unexpected changes, according to Dr Trevor Bedford at the Fred Hutchinson Cancer Research Center in Seattle, Washington.
The coronavirus, named SARS-2, has now infected more than 64,000 people and killed 1,383.
A scientist who has been studying the SARS-2 coronavirus said there was nothing about it which suggested it had been genetically engineered.
Dr Bedford said: 'There’s no evidence whatsoever of genetic engineering that we can find,' the Financial Times reported.
He spoke at a meeting of the American Association for the Advancement of Science (AAAS) in Seattle.
'The evidence we have is that the mutations [in the virus] are completely consistent with natural evolution.'
Viruses mutate naturally over time as they come into contact with more things which could kill them.
They adapt and change in order to survive, which can make it more difficult to treat or stop them.
Dr Bedford said the mutations seen in the coronavirus, which is being closely examined by scientists the world over, did not appear to be anything abnormal.
One of the triggers of the man-made virus theory was a scientific paper published by researchers in India which said the virus looked suspiciously similar to HIV.
The paper has since been taken back but the rumours it started continue to circulate online.
Dr Bedford said the parts of the viruses which looked similar look similar in various places throughout nature - 'again and again throughout the tree of life', he said.
Claims that the SARS virus escaped from inside biology labs in Beijing added fuel to allegations that a lab in Wuhan could be the source of the outbreak.
A high-security lab was set up there in 2017 and Tim Trevan, a biosafety consultant in Maryland, warned at the time that China's secretive culture could make it risky because 'structures where everyone feels free to speak up and openness of information are important.'
But a Rutgers University expert, Dr Richard Ebright, told DailyMail.com that 'there's no reason to harbour suspicions' that a lab was to blame.
The widely held belief is that the coronavirus, which triggers a pneumonia-causing disease called COVID-19, has come from bats.
A study found the virus is 96 per cent identical to one discovered in bats, and it is believed that a second, intermediary animal caught it from a bat and then spread it to humans at a livestock market.
Dr Bedford's comments come as China has reportedly appointed its top military biological weapon expert to run the virus lab in Wuhan.
Chen Wei, a major general of the People's Liberation Army, has taken the helm at the Wuhan Institute of Virology.
Ms Chen has experience in fighting the SARS outbreak 18 years ago and in trying to develop a vaccine for Ebola.
Speaking about the coronavirus, she reportedly said: 'The epidemic is like a military situation. The epicentre equals the battlefield.'