The Indian Covid-19 variant has been detected in several areas of England which are recording the highest number of infections in the country, data suggests.
Data from Public Health England (PHE) shows a rise in cases of the Indian variant of concern from 520 to 1,313 this week in the UK.
PHE said infections were "rising in the community" and it was assessing the impact and severity.
The majority of the 1,313 cases of the B16172 variant, which was first identified in India, are in England, with PHE reporting 35 in Scotland, 11 in Wales and 12 in Northern Ireland.
The government has said they could not rule anything out when it comes to tackling an outbreak of the variant.
Asked if the variant has the potential to cause a delay to the planned reopening on June 21, Nadhim Zahawi said: "We take nothing off the table, we will do everything, whatever it takes to bring the infection rates under control."
Most of the cases have been detected in the North West of England with some in London.
The variant has been detected in Bolton, Greater Manchester, Blackburn in Lancashire, and Sefton in Merseyside, which have all seen rates rise rapidly.
Many of the areas currently seeing a surge in the Indian variant are the same areas that have struggled with high infection rates throughout the course of the pandemic.
More vaccine doses have been sent to Bolton, which has a particularly high rate of the Indian variant, while 800,000 PCR tests have been sent to 15 areas of England, including parts of London and Merseyside.
Although the Indian variant is thought to be highly transmissible, vaccines are expected to be effective against it.
Bolton has the highest rate of any local area in England, with 553 new cases in the seven days to May 9 – the equivalent of 192.3 per 100,000 people.
This is up from 84.9 in the seven days to May 2.
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In Bolton, mobile testing units have been deployed and door-to-door PCR testing has been offered to 22,000 residents, while a vaccine bus has been set up to increase uptake among those who are eligible and a rapid response team of 100 nurses, public health advisers and environmental health officers has been sent in.
Erewash in Derbyshire has the second highest rate in the country, but this has been driven by an outbreak at Wilsthorpe Academy in the town of Long Eaton, according to Derbyshire County Council’s director for public health, Dean Wallace.
Blackburn with Darwen in Lancashire has the third highest, up from 54.1 to 107.6, with 161 new cases, followed by Bedford where the rate has more than doubled from 39.8 to 86, with 149 new cases.
Blackburn with Darwen Council said on Thursday that it would be offering vaccines to all over-18s from next week following the increase in cases, but later said that, although additional vaccine clinics are being set up, the jab will only be offered to those eligible under current Government guidance.
Greater Manchester mayor Andy Burnham has submitted a request to the Joint Committee on Vaccination and Immunisation for all over-16s in Bolton, along with the rest of the Greater Manchester area, to receive a vaccination “to mitigate the risks of spread in those communities where we are seeing more transmission”.
Bedford Borough Council on Thursday called for vaccines to be made available for over-16s in the area due to the rapid rise in cases, including the Indian variant.
It said it had been notified of a number of cases of the variant with “mounting evidence that this variant is spreading rapidly in the borough”.
In the Formby area of Sefton, Merseyside new drive-through and walk-through test centres were set up on Friday, specifically to identify the Indian variant.
The latest case rate in Sefton was 53.9, up from 26 the previous week, with 149 new cases.
Measures have also been brought in elsewhere, including in parts of London.
Hounslow is the London borough with the highest rate at 48.2 per 100,000 people in the seven days to May 9, with 131 new cases.
The Government says surge testing is taking place across London in targeted locations in Hillingdon, Hounslow, Redbridge, Tower Hamlets and the Royal Borough of Kensington and Chelsea.
It is not clear from the website whether this is to identify the Indian variant or other variants more generally.