The government’s scientific advisers called for a short lockdown in England to halt the spread of Covid-19 last month, newly released documents show.

The experts said an immediate “circuit breaker” was the best way to control cases, at a meeting on 21 September.

Communities Secretary Robert Jenrick insisted the government had taken “robust action” that “balanced” the impact on the economy.

But Labour has described the documents as “alarming”.

It comes as the Liverpool region prepares to enter a “very high” Covid alert level from Wednesday, the highest of a new three-tier system.

Most areas of England will be on “medium” alert, with measures such as the rule of six, but areas with local restrictions on household mixing are automatically on “high” alert.

A “very high” alert sees pubs and bars close if they do not serve “substantial meals”, almost all household contacts banned and advice against travel.

Speaking at a press conference on Monday evening, Boris Johnson said the alert system for England could succeed in driving cases down if it was implemented “very effectively”, and he rejected the “extreme route” of a full nationwide lockdown “right now”.

But at the same briefing, England’s chief medical officer, Prof Chris Whitty, voiced concerns over the impact of the new rules, saying he was not confident the “base measures” in the highest tier “would be enough to get on top of” the virus.

“That is why there’s a lot of flexibility for local authorities […] to do significantly more,” he said.

Released shortly after the announcement, minutes from the meeting of the Scientific Advisory Group for Emergencies (Sage) – which feeds into UK government decision making – stated the advisers had called for the immediate introduction of a short national lockdown three weeks ago.

Of all the measures proposed by the advisory group, just one – advising those who can work from home to do so – was implemented by the government at the time.

In the documents, Sage warn

Speaking to BBC Breakfast, Mr Jenrick said the government had introduced measures such as the rule of six at the time, and stressed the Sage papers had contributed to the measures the PM announced on Monday.

He said they had taken “balanced judgements” that weighed up the effect on the economy and “all the other unintended consequences” of measures, such as the impact on mental health and delayed surgeries.

On the new three-tiered system, he said: “We are now able to have a very clear and consistent framework across the whole country, so people will be able to understand approximately what the rate of infections is in their own area and what the rules are accordingly.”

He later told BBC Radio 4’s Today programme that the baseline measures for the highest tier “will have an impact”, and ruled out any other areas joining the Liverpool City Region in the highest tier this week.

But he said plans for other parts of the nation would be “kept under review”.

Labour’s shadow health secretary Jonathan Ashworth told BBC Breakfast he was “alarmed” by the Sage papers, adding: “Ministers need to tell us why they’ve rejected that advice to go further.”

He also insisted the government was going to have to go further than the latest measures.

ed that “not acting now to reduce cases will result in a very large epidemic with catastrophic consequences”.