The UK recorded 6,238 Covid cases on Friday, the highest number in more than two months.
The latest government figures also show there have been 11 deaths.
The number of cases is the highest since 25 March, when 6,397 were recorded.
New coronavirus cases involving the Indian variant have increased by 79 per cent compared with last week. The strain is now believed to be dominant in the UK.
There are 12,431 confirmed cases of the Indian variant, also known as Delta, in the UK, up from 6,959 last week.
Early evidence from Public Health England (PHE) published on Thursday suggests this version of Covid-19 may lead to an increased risk of being admitted to hospital compared with the previously dominant Kent variant (Alpha).
Meanwhile, another potential coronavirus variant, thought to be linked to Nepal, has also been seen in the UK.
This version is believed to be a mutated version of the Indian variant, with a spike mutation, known as K417N.
Experts believe this mutation may have the potential to make vaccines less effective – although it is too early to tell without further investigations.
On Friday a further 191,266 people received a first dose of a Covid vaccine, and another 377,641 received the second dose.
This brings the total number of people who are fully vaccinated to 26,799,944, while 39,949,694 people have now received at least one dose.
There have now been 127,823 official coronavirus deaths recorded in the UK.
However, separate data based on death certificates records the toll as 152,183.
Health experts have warned that the Delta variant may lead to an increased risk of hospital admission.
Some 278 people with the Indian variant attended A&Es in England in the past week, resulting in 94 people being admitted to hospital overnight, according to Public Health England (PHE).
This compares with 201 A&E attendances in the previous week, with 43 admissions.
However the majority of admissions continue to be people who have not been vaccinated, PHE said.