There are signs the UK is in the early stages of a third wave of coronavirus infections, a scientist advising the government has said.
Prof Ravi Gupta, from the University of Cambridge, said although new cases were "relatively low" the Indian variant had fuelled "exponential growth".
He said ending Covid restrictions in England on 21 June should be postponed.
Environment Secretary George Eustice said the government could not rule out a delay to the planned lockdown easing.
But business leaders have warned of the harmful impact of any change to the proposed dates.
On Sunday, the UK reported more than 3,000 new Covid infections for a fifth day in a row.
Prior to this, the UK had not surpassed that number since 12 April.
Prof Gupta told BBC Radio 4's Today programme the UK was already in a third wave of infections and at least three quarters of cases were the variant identified in India.
He said: "Of course the numbers of cases are relatively low at the moment - all waves start with low numbers of cases that grumble in the background and then become explosive, so the key here is that what we are seeing here is the signs of an early wave."
However, he said the number of people who had been vaccinated in the UK meant this wave would probably take longer to emerge than previous ones.
"There may be a false sense of security for some time, and that's our concern."
The final stage of the government's roadmap for lifting lockdown
would remove all limits on how many people you can meet - either indoors or outdoors.
But Prof Gupta - a member of the government's New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) - said ending restrictions in June should be delayed "by a few weeks whilst we gather more intelligence".
"If you look at the costs and benefits of getting it wrong, I think it is heavily in favour of delay, so I think that's the key thing," he added.
Full article
Covid-19: UK in early stages of third wave - scientist