Japan is working to isolate and analyse a new variant of the coronavirus detected in four people who arrived from Brazil, AFP reported, quoting a health ministry official.

Japan announced the detection of the new variant on Sunday, but officials have been at pains to emphasise there is no evidence yet that it is any more transmissible or dangerous than others.

“In order to further analyse the variant, we need to isolate it first,” a health ministry official told AFP.

“It's hard to say right now when we can release the details,” he said, adding the process could take weeks or months.

The variant was found in two adults and two children who arrived in Japan on January 2 from Brazil.