The death count also increased to 1,74,308 with 1,185 new fatalities, the highest since September 19, 2020.
There were 1 in 480 people infected in the week ending April 10, according to the latest figures, down from 1 in 340 infected the week before.
In Northern Ireland, the estimate was around one in 710 people, a drop from one in 300 in the previous week and the lowest since estimates began for the nation in October.
Six hundred cases - rising by 56 in a week - of the South African strain were identified in the UK.
A No 10 spokesman said today: 'We add and remove countries based on the latest scientific data and public health advice from a range of world-leading experts.
Downing Street has defended leaving India off the hotel quarantine list and said the register is "under constant review".
Registering a steady increase for the 36th day in a row, the active cases have increased to 14,71,877 comprising 10.46 per cent of the total infections, while the national COVID-19 recovery rate has dropped to 88.31 per cent.
According to Public Health England, 77 confirmed cases of the "B.1.617 strain" have so far been identified in the United Kingdom - 73 in England and four in Scotland.
But the "double mutation" on its own isn't unusual and has been found in other variants.
Officials said there is now no evidence to suggest that disease from the newly identified variant is more serious than previous ones, nor is there current evidence to suggest vaccines are less likely to work against it.
That's despite experts believing that the Indian variant not only speeds up transmission, but also features an "escape mutation" which could possibly impact on the effectiveness of vaccines.
Prof Altmann said he found it "mystifying" and "slightly confounding" that those arriving from India are not subject to a hotel quarantine. This was first detected and reported by India, it has two mutations: the E484Q and the L452R. "They are a worry".
The report is an incomplete representation of Indian data and different areas in the country have different dominant variants, they said.
The Guardian reported that it had seen leaked emails which indicated senior officials were considering scaling back extensive asymptomatic testing due to the number of false positives.
We have been in close contact with the Indian government about the Prime Minister's upcoming visit in light of the COVID-19 situation in India.
When the figure is above 1, an outbreak can grow exponentially, but when it is below 1, it means the epidemic is shrinking.
The Joint Committee on Vaccination and Immunisation (JCVI) had previously only recommended that Covid-19 jabs be offered to pregnant women when their risk of exposure to the virus is high, such as health workers, or if a woman has underlying health conditions.