BEIJING (XINHUA) - Medical researchers have found that a freezer cabinet in a laboratory in Phnom Penh and an irrigation pipe in a wildlife sanctuary in Thailand are "not the most obvious places" for tracing the origin of Covid-19, according to a recent report published by South China Morning Post.

A team of researchers in the Institut Pasteur in Cambodia studied more than 400 samples collected from bats on field trips and kept in biobank freezers. There, they found a decade-old bat pathogen seen as one of the closest known relatives to the Sars-CoV-2 virus, which is linked to the deadly Covid-19 pandemic. The virus was "92.6 per cent identical" to the one that causes Covid-19, making it among the first found outside China.

But unlike Sars-CoV-2, there was no indication this virus could infect people, the researchers said. The results came weeks before a batch of researchers in Thailand published findings from samples taken from 100 bats living in an irrigation pipe in a wildlife sanctuary, in which a virus was discovered 91.5 per cent identical to Sars-CoV-2 virus at the whole genome level, said the report.

The other was an indication from blood tests that some of the bats had previously been infected with a virus that was even closer to the one that causes Covid-19 than the virus they uncovered there, according to Dr Wang Linfa, director of the emerging infectious diseases programme at Duke-NUS Medical School in Singapore.

Those findings reportedly indicate a wide range of related viruses in Asia. Dr Wang said it was possible the Sars-CoV-2 bat ancestor virus, or the virus in an intermediate animal, could be in South-east Asia, where there was greater bat diversity than in China.