The rapid spread of the Indian coronavirus variant could lead to the return of local lockdowns in England, government ministers have acknowledged.

The rise in cases of the highly transmissible B1617.2 variant also risks the next stage of England’s road map out of lockdown – currently pencilled in for 21 June – being pushed back.

Health secretary Matt Hancock has said there have been 2,323 confirmed cases of the variant of concern in the UK – with cases doubling in some parts of the country over the last week.

Data from the Wellcome Sanger Institute – based on recent surge testing – shows how rapidly the Indian variant has spread across England.

There has been a 44 per cent increase in the number of areas in England detecting the Indian variant over the past week. The variant of concern was found in 127 areas in the week ending 8 May, compared with 71 in the week before.

However, most areas have under five cases – and health authorities in 40 of the 127 areas have only identified one case of the variant so far.

The Wellcome Sanger Institute data shows Indian variant hotspots in London, some parts of the south and Midlands, and across much of north west – particularly in Bolton and Blackburn with Darwen.

The average number of weekly Indian variant cases in Bolton is 210, according to the institute’s analysis of fully processed cases over the past fortnight – though the total number of variant cases will be higher.

The next worst-affected area in Blackburn with Darwen, which has seen 76 cases average weekly cases over the past fortnight. Sefton in Merseyside has seen 62 cases and Bedford has seen 49 cases, according to the rolling average.

Bolton and Blackburn are the areas ministers remain most concerned about. An estimated 64.1 per cent per cent of over-16s in Bolton had received a jab as of 9 May, with 33.5 per cent having had both doses.

In Blackburn the figures were 60.6 per cent for one dose and 28.8 per cent for two – slightly lower than the national average. Across England 64.8 per cent had received first doses and 33 per cent both jabs as of 9 May.

The government’s Sage advisory group has said there is a “realistic possibility” than the transmissibility could be 50 per cent higher than the variant first detected in Kent.

If the variant proves to be 40 to 50 per cent more transmissible, the scientists predicted that would “lead to a much larger peak” of cases, hospitalisations and deaths than previous waves.