The European Medicines Agency said Thursday a coronavirus variant known as "Mu" could be cause for concern, although there is no data yet to show it will overtake the dominant Delta strain.

Mu, which was first identified in Colombia in January and is known scientifically as B.1.621, was classified earlier this month as a "variant of interest" by the World Health Organization.

The EMA, while mainly focused on the highly transmissible Delta variant, is "also looking into other variants that might be spreading, like the Lambda one (identified in Peru) and more recently the Mu one," its vaccines strategy chief Marco Cavaleri told a press briefing.

"The Mu one being potentially more of concern because of the potential increased immune escape that it may show."

The Amsterdam-based regulator, which checks medicines for the 27-nation EU, will discuss with vaccine developers the effectiveness of current jabs in tackling the Mu variant, Cavaleri added.

"However, I have to say that we don't have yet data that would show that the Mu variant is spreading that much, and whether it will have any chance to overtake the Delta variant as a dominant strain."

All viruses, including SARS-CoV-2 that causes Covid-19, mutate over time. Most mutations have little or no effect but some can influence properties of viruses including how easily they spread, the severity of the disease they cause, and their resistance to vaccines.

The WHO currently identifies four Covid-19 variants of concern, including Alpha, which is present in 193 countries, and Delta, present in 170 countries.

Five variants, including Mu, are to be monitored.

After being detected in Colombia, Mu has since been reported in other South American countries and in Europe.

The WHO said its global prevalence has declined to below 0.1 percent among sequenced cases. In Colombia, however, it is at 39 percent.