WASHINGTON, Dec. 29 (CNA) - The first known US case of a highly infectious coronavirus variant was detected in Colorado, Colorado Governor Jared Polis said on Tuesday (Dec 29).

Polis announced on Twitter that his state had discovered a case of a highly infectious coronavirus variant B117 first detected in the United Kingdom.

He attached an official statement from his office and state health officials that said the individual is a "male in his 20s who is currently in isolation in Elbert County and has no travel history."

The individual had no close contacts, the statement said, but the situation will continue to be monitored "very closely" and authorities are working to identify other potential cases through contact tracing.

The Washington Post reported that the Colorado case is the first known infection of the variant virus to be recorded in the United States. The first two variant cases on the North American continent were discovered in Canada over the weekend.

Fears have been raised by the new strain of COVID-19, which experts say is potentially more transmissible.

More than 3,000 cases of the variant have already been reported in the UK and dozens of countries in Europe and around the world, according to the EU health agency ECDC.

In South Africa, more than 300 cases of another variant have been recorded. Three cases of that strain variant have been confirmed in Europe - two in the UK and one in Finland - but all three have been connected to people returning from South Africa.