Professor Tom Jefferson, of Oxford University's Centre for Evidence-Based Medicine (CEBM), pointed to a string of recent discoveries of the infection's presence around the world before it emerged in Wuhan in December, the Daily Mail reported.
Traces of COVID-19 have been found in sewage samples from Spain, Italy and Brazil which pre-date its discovery in China.
Discussing the possibility the virus didn't originate in China, Professor Jefferson told The Daily Telegraph: 'Strange things like this happened with Spanish Flu.
'In 1918 around 30 per cent of the population of Western Samoa died of Spanish Flu, and they hadn’t had any communication with the outside world.'
He added: 'The explanation for this could only be that these agents don’t come or go anywhere.
'They are always here and something ignites them, maybe human density or environmental conditions, and this is what we should be looking for.'
Professor Jefferson told the newspaper he believes virus may be transmitted through the sewage system or shared toilet facilities.
The virus — called SARS-CoV-2 — is believed to be mainly spread through droplets expelled by talking, coughing and sneezing.
Virologists in Spain last week claimed they found traces of the disease in samples of waste water from March 2019, almost a year before it struck Europe.
Scientists suggested it went under the radar at the time 'because it was flu season and nobody was looking for it'.
But other experts questioned how it was possible for the virus — known to be contagious — to exist at detectable levels but not cause outbreaks.
Italian health chiefs also found sewage water was contaminated with the virus in the cities of Milan and Turin in December.
And Brazilian researchers claimed they found traces of the virus when they analysed waste water samples taken from Florianopolis in November.
Scientists remain baffled as to how the virus jumped to humans. It has been linked to bats, pangolins and snakes.
Experts have repeatedly claimed the coronavirus may have been lurking in animals for decades before adapting to be able to strike humans.
Sir Jeremy Farrar, director of the UK-based global health charity Wellcome, told MailOnline in January: 'This is absolutely not a brand new virus.
'This will have been circulating in animals in China and maybe other parts of Asia, probably for years... if not decades.'
He added that it probably hadn't had an effect on humans until now, or caused such mild infections that 'no-one was bothered about' it.
But Sir Jeremy said 'something changed', claiming the virus may have adapted to animals or mutated to become infectious to humans.
It comes after a record 212,326 new cases of coronavirus were diagnosed worldwide on Saturday, according to the World Health Organization.
The staggering figure — mainly driven by the US and Brazil — was an 11 per cent rise on the previous record of 190,566, set on June 28.
June was the most devastating month for the global pandemic and saw cases top 10million and deaths surge past 500,000.
The 10million milestone was hit only last week and the total has since risen to 11.4m, meaning more than 1.4million people have been diagnosed in seven days.
Although many countries in Europe are now emerging from the worst days of the global crisis, the pandemic still rages on in the Americas and Asia.