Six cases of the Brazilian COVID-19 variant, known as P1, have been identified in the UK, Public Health England (PHE) said on Sunday.
Three cases were detected in England's South Gloucestershire area and the other three in Scotland, which are not linked to the England cases.
The UK government is considering taking tougher border measures after officials said they were trying to identify the third English case because the person did not complete their test registration card, according to PHE.
Susan Hopkins, PHE's strategic response director for COVID-19, later told reporters that the P1 cases had been discovered "thanks to the UK's advanced sequencing capabilities which means we are finding more variants and mutations than many other countries and are therefore able to take action quickly".
"The important thing to remember is that COVID-19, no matter what variant it is, spreads in the same way. That means the measures to stop it spreading do not change", she emphasised.
She was echoed by Scottish Health Secretary Jeane Freeman who said the P1 variant "demonstrates how serious coronavirus is and reinforces the need to minimise the spread of the virus".
Freeman added that the government would "encourage everyone across the country to adhere to the necessary public health restrictions by staying at home except for essential purposes as this is the single best way of staying safe and stopping" the spread of P1.
Shadow Home Secretary Nick Thomas-Symonds, for his part, said "it is deeply concerning" that the Brazilian coronavirus variant had been found in the UK.
"It is now vital that we do everything we can to contain it. But this is further proof that the delay in introducing a hotel quarantine was reckless and the continuing refusal to put in place a comprehensive system leaves us exposed to mutations coming from overseas", he pointed out.
P1 is thought to have originated in the northern Brazilian city of Manaus in December and has since been found in Japan and a spate of European countries.
What is Known About P1 So Far
The variant, also known as the B1128, was first detected in Japanese travellers who visited Brazil, according to the Centres for Disease Control and Prevention (CDC).
The strain was designated "of concern" given that it shares some mutations with the variant that was first identified in South Africa and is thought to respond less well to current vaccines.
The developments come after more than 20 million people in the UK were given their first COVID-19 vaccine dose, which was touted by Health Secretary Matt Hancock as a "magnificent achievement for the country".
The remarks followed Prime Minister Boris Johnson unveiling a "roadmap" last week to get the UK out of the nation's third coronavirus lockdown on a step-by-step basis. As of 28 February, the number of confirmed COVID-19 cases in the UK had soared to 4.1 million, with 122,705 fatalities, according to the World Health Organisation's latest situation report.