The World Health Organization (WHO) says it is monitoring a new form of the coronavirus Delta variant.
The virus, named AY4.2, has two additional mutations, the WHO said on Thursday.
Recently, experts had reported a minor outbreak of the variant in Britain. Russia also recorded its first cases, according to a report by the Interfax news agency.
There have also been cases of AY4.2 reported in the United States, Denmark, and Germany.
Germany's Robert Koch Institute for disease control and prevention reported that the Delta subvariant has been detected about 280 times in the country since the July.
Only a small proportion of Germany's coronavirus samples are tested for virus variants. But the institute says assessments indicate that the prevalence remains very low.
Researchers do not yet believe that the mutated variant could be significantly more contagious than the original Delta variant, which was first detected in India in late 2020. It is now the dominant strain worldwide.
