A “sudden influx” of people holidaying in Cornwall over half term is likely to be a factor in an increase in cases there, Professor Tim Spector said.

One local councillor described a recent rise in cases as a “tsunami” in the wake of the G7 summit held there earlier this month, but the Government denied a link between the two.

Prof Spector, professor of genetic epidemiology at King’s College London and lead scientist on the Zoe Covid study app, said data this week shows “rates in former hotspots, such as Scotland and the north west of England, continuing to plateau”.

But he added: “At the same time, top UK holiday destinations like Cornwall are emerging as new areas with rapidly increasing cases.

“I think this is down to a number of factors, including the sudden influx of holidaymakers over half term, as well as the recent G7 summit and a previously unexposed local population.

“We need to remain vigilant of these UK holiday destinations as summer holidays approach, and ensure that we minimise outbreaks by following government guidelines.”

The latest local authority area figures show that Cornwall and Isles of Scilly had 857 new cases recorded in the seven days to June 19, up from 411 the previous week.

The long-running Zoe study estimates that among unvaccinated people in the UK there are currently 15,099 new daily symptomatic cases of Covid-19 on average, based on PCR test data from up to five days ago.

This is up from 12,830, an increase of 18%, last week.

There are 4,023 new daily symptomatic cases of the virus in partly or fully vaccinated people, the study suggests.

This is an increase of 37% from 2,930 new cases last week.

Those behind the study said their data continues to show a higher positivity rate in people who have had only a first dose of vaccine, compared with those who are double jabbed.