Concerns are mounting over a new variant of COVID-19, but scientists say it's still too early to know for sure if the virus has mutated again.
Reports of the possible new variant were sparked after the UK removed Portugal from its 'green list' for travel earlier this week, citing the existence of a "Nepal mutation" in the country.
Being on the UK's green list means British tourists can visit a country without having to go into quarantine for 10 days when they return home.
But UK's Transport Minister Grant Shapps said Portugal had now been shifted to the 'amber' travel list, meaning Brits who visit the country would need to self-isolate at home for 10 days upon returning to Britain, as well as undergoing a test for COVID-19 on or before day two and on or after day eight.
In announcing the change of category, Shapps blamed the move on a "sort of Nepal mutation of the so-called Indian variant" in Portugal.
"We just don’t know the potential for that to be a vaccine-defeating mutation and simply don't want to take the risk as we come up to June 21 and the review of the fourth stage of the unlock," The Guardian reported Shapps as saying.
Despite Shapps' comments, scientists say it's still unclear whether such a mutation really exists or not.
"We don't actually really know if a variant exists or if we should be concerned at the moment," Dr Jemma Geoghegan, an evolutionary virologist at the University of Otago, told Newshub.
She said although it was a possibility the new variant existed, Nepal has not publicly released enough genome data for scientists to confirm or deny the reports.
"Until they publicly share data it can't really be recognised as a variant," Dr Geoghegan said.
According to the Daily Mail, the potential new strain has already been detected in more than 40 Britons, and combines mutations from the Indian and South African variants of the virus.
According to the newspaper, scientists believe Nepal is the most likely origin of the strain due to its similarities with the Indian variant, and because it has been detected in a large number of passengers flying out of the country.
The Daily Mail also said the strain was "potentially more infectious and vaccine resistant" than other variants.
A spokesperson for Nepal's Ministry of Health and Populations told the PTI news agency that media reports of the new strain were simply "not true".
And on Thursday, the World Health Organisation (WHO) in Nepal also said it was "not aware" of any new variant.
In a tweet, the organisation said the only confirmed variants of COVID-19 circulating in the country are Alpha (B.1.1.7) - commonly known as the UK variant - Delta (B.1.617.2) - the Indian variant - and Kappa (B.1.617.2) - another strain of the Indian variant.
In order not to stigmatise countries where new mutations are discovered, the WHO recently renamed the various variants using letters from the Greek alphabet.
There are currently four "variants of concern", which the WHO lists as the Alpha, Beta, Gamma and Delta variants - formerly known as the UK, South African, Brazilian and Indian variants, respectively.
The organisation lists a further six "variants of interest", the Epsilon, Zeta, Eta, Theta, Iota and Kappa.