The United Kingdom has branded a coronavirus strain first detected in India as a "variant of concern" as cases more than doubled in a week.

According to Sky News, the designation of the B1617.2 COVID-9 variant raises the prospect of surge testing in infection hotspots to curb transmission.

The latest development comes as the U.K. government is expected to announce quarantine-free holiday destinations with the expected lifting of the ban on foreign breaks from 17 May.

The B1617.2 COVID-9 variant is one of three related coronavirus strains first seen in India which have been detected in the U.K. and designated "under investigation" by PHE. The others are B1617.1 and B1617.3.

Health authorities say they "haven't seen any hint" any COVID strain can evade the vaccines.

The Sky News report notes that the cases of B1617.2 have increased to 520 from 202 over the last week and almost half the cases are related to travel or contact with a traveler.

U.K. Prime Minister Boris Johnson said the country will embark on "making sure that we are absolutely ruthless in the surge testing."

"At the moment we're looking carefully at the way the Indian variant seems to function, we don't see any evidence that it is resistant to the vaccines or in any way more dangerous," he added.