London, May 30 : The coronavirus disease did not develop naturally, but was created by Chinese scientists in a Wuhan lab, who then tried to cover their tracks by reverse-engineering versions of the virus to make it look like it evolved naturally from bats, according to a breakthrough research conducted by a team of researchers. The research, conducted by British Professor Angus Dalgleish and Norwegian scientist Birger Sorensen, is forthcoming in the scientific journal Quarterly Review of Biophysics Discovery, the DailyMail.com reported on Friday. In the 22-page paper, the researchers describe their months-long "forensic analysis" into experiments done at the Wuhan lab between 2002 and 2019. It concludes that "SARS-Coronavirus-2 has no credible natural ancestor" and that it is "beyond reasonable doubt" that the virus was created through "laboratory manipulation". The paper also alleges of "unique fingerprints" in Covid samples that could only have arisen from manipulation in a laboratory and that "the likelihood of it being the result of natural processes is very small". "A natural virus pandemic would be expected to mutate gradually and become more infectious but less pathogenic which is what many expected with the Covid-19 pandemic but which does not appear to have happened," the scientists wrote in the paper, according to the Daily Mail report. "The implication of our historical reconstruction, we posit now beyond reasonable doubt, of the purposively manipulated chimeric virus SARS-CoV-2 makes it imperative to reconsider what types of Gain of Function experiments it is morally acceptable to undertake. Because of the wide social impact, these decisions cannot be left to research scientists alone," they added. Dalgleish and Sorensen wrote that they have had "prima facie evidence of retro-engineering in China" for a year, but their theory was rejected by academics and major journals, the report said. Dalgleish is a professor of oncology at St George's University, London, while Sorensen is a virologist and chair of pharmaceutical company Immunor. Many experts have until recently denied the lab-leak theory and claimed that Covid-19 originated as a natural infection leaping from animals to humans. But now there has been a shift. A team of 18 scientists from Universities in the US, Canada, the UK and Switzerland have signed a letter in the journal Science arguing the need to determine the origin of the Covid-19 pandemic. The US' top infectious disease expert Anthony Fauci also said he is "not convinced" Covid-19 developed naturally. US President Joe Biden, last week, ordered the intelligence community to re-double efforts to examine how the virus originated, including the lab accident theory. The European Union, the UK, Australia and Japan also have joined the US in seeking a deeper probe into the origins of the pandemic. /IANS