All but one of the Lambda variant cases have been linked to travel, according to the latest update from Public Health England (PHE).
On Tuesday there were 6 cases of the Lambda strain in the UK between February 23 and June 7.
Four cases were discovered in London, one in the southwest of England and one in the West Midlands.
Five of the cases had a history of overseas travel, and for one case the travel status is unknown, PHE said.
No deaths have been linked to the strain, officially known as C.37, in the past 28 days, according to the update.
The new strain was placed in the variant category under investigation by PHE on Wednesday because its mutation is believed to be more infectious and with increased resistance to antibodies, according to the health organization.
The World Health Organization (WHO) considers it a variant of interest, and it has been monitored by UK public health authorities since mid-April.
Scientists are still investigating whether the mutation increased transmissibility or resistance to antibodies neutralizing the virus.
The first documented Lambda case was found in Peru, where it now accounts for over 80% of all cases.
It has been sequenced in 26 countries to date, PHE said.
Cases have emerged in South and Central America and the United States, and very small numbers have been found in parts of Europe, according to the health body’s count.
The delta variant, which first appeared in India, remains the dominant strain in the UK – accounting for over 95% of all infections, according to the latest PHE update.
PHE is currently performing laboratory tests to better understand the variant.
There was a 79% increase in one week in delta variant cases across the UK, PHE also revealed as 15,810 new infections were reported on Friday.
PHE data shows that 75,953 confirmed and probable cases of the delta variant of Covid-19 were found, an increase of 33,630 from the previous week.
Of the 75,953, some 70,856 were in England, 4,659 in Scotland, 254 in Northern Ireland and 184 in Wales.
Dr Jenny Harries, chief executive of the UK Health Security Agency, said the increase across the UK is due to younger age groups, many of whom have now been urged to get vaccinated as the rollout of the vaccine extends to anyone 18 years of age and over.
Almost 44 million first doses and over 32 million second injections have been administered.
And although hospital cases have also nearly doubled, most patients in need of treatment have not received a vaccine, officials say.
It came as Boris Johnson said he was “very confident” that the remaining coronavirus restrictions in England will be lifted on July 19. after “freedom day” was delayed by a month
The Prime Minister said: “I am very confident that we will be able to move to step four of the roadmap according to the timetable that I have established by dealing with July 19, as I said, as a Date terminus.
“I think that’s definitely what the data continues to indicate. “