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The government should have imposed the coronavirus lockdown earlier and its failure to do so has cost lives, a scientific adviser to the government has said.

Professor John Edmunds, who sits on the government’s scientific advisory group for emergencies (Sage), said it would have been “hard” to lock down earlier as the government’s data and awareness of coronavirus was “really quite poor”.

But health secretary Matt Hancock insisted the government made the “right decisions at the right time”.

The clash came amid reports that Boris Johnson will set out further steps to ease the lockdown, which was introduced on March 23, following a cabinet meeting this week.

But it comes after a period in which the prime minister has presided over the UK suffering one of the worst Covid-19 death tolls in the world.

Edmunds, an infectious diseases expert from the London School of Hygiene and Tropical Medicine, told BBC One’s Andrew Marr Show: “We should have gone into lockdown earlier. 

“I think it would have been hard to do it. I think the data that we were dealing with in the early part of March and our situational awareness was really quite poor.

“And so, I think it would have been very hard to pull the trigger at that point.But I wish we had.

“I wish we had gone into  lockdown earlier. I think that has cost a lot of lives unfortunately.”

Asked about Edmunds’ comments, Hancock told Marr: “I think we took the right decisions at the right time. 

“And there’s a broad range on Sage of scientific opinion. 

“And we followed, we were guided by the science which means guided by the balance of that opinion as expressed to ministers through the chief medical officer, and the chief scientific adviser.”

Asked again about Edmunds’ comments, Hancock said: “There are others who equally make different scientific arguments.”

Asked if he knew anyone who thought locking down relatively late compared to other countries did not cost lives, the health secretary said: “Yes if you listen to the balance of opinion on Sage, 100 people on Sage approximately.”

Marr then asked: “So absolutely clear, you are sure that locking when you did and not earlier did not cost lives?”

Hancock said: “I am sure, and we keep looking back on that period. 

“I’m sure that taking into account everything we knew at that moment, my view is that we made the right decisions at the right time.”

The health secretary meanwhile claimed it was “not true” that testing figures are designed by the government to show the largest possible number of tests.

In a rebuke to Hancock last week, UK Statistics Authority chairman Sir David Norgrove said: “The aim seems to be to show the largest possible number of tests, even at the expense of understanding.”

But Hancock insisted: “The thing about it is that it is not true. There are other ways that you could measure testing to give much higher figures and we chose not to.

“What we chose, advised by my permanent secretary, are the most accurate ways to show the testing that the government is doing, which is the number of tests either directly administered or sent out.”

He was unable to give the latest figures for the number of people tested – as opposed to the number of tests.