An Indian-origin scientist, who is advising the British government, warned that there are signs the UK is in the early stages of a third wave of coronavirus infections, and urged Prime Minister Boris Johnson to delay the planned June 21 reopening of the country by a few weeks, according to a media report on Monday.

Prof. Ravi Gupta of the University of Cambridge, who is a member of the government’s New and Emerging Respiratory Virus Threats Advisory Group (Nervtag), said although new cases were “relatively low” the B.1.617 variant of the Covid-19 had fuelled “exponential growth”, the BBC reported.

On Sunday, the UK reported more than 3,000 new Covid-19 infections for a fifth day in a row. Prior to this, the UK had not surpassed that number since April 12.

Gupta also called on Boris to delay the planned June 21 reopening of the country by “a few weeks”.

The UK’s overall Covid-19 caseload and death toll currently stood at 4,499,939 and 128,043, respectively.

Gupta said the UK was already in a third wave of infections and at least three-quarters of cases were of the new variant, first discovered in India.

“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,” he said.

However, he said the number of people who have been vaccinated in the UK meant that 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.”

More than 38.8 million people, or more than 70 per cent of adults in Britain, have been given the first jab of the coronavirus vaccine, according to the latest official figures.

Gupta also said ending restrictions on June 21 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.

Prof. Adam Finn, another leading scientific adviser to the government, also urged caution over the June 21 date for easing restrictions.

Environment secretary George Eustice said the government could not rule out a delay to the planned easing of the lockdown. He told the BBC that the government had to take things “one step at a time”.