The UK could be heading for another full lockdown by next month, the former government chief scientific adviser has warned.

Sir David King claimed we are “nowhere near” the safe reopening of schools - and that Prime Minister Boris Johnson must now act immediately to prevent national restrictions being put in place, the Mirror reports.

He said: “We need a proper test and trace system by September. Otherwise full school opening will put us right back.”

He also urged Boris Johnson to "get it right" this month - or face a second wave of coronavirus infections, as he criticised the government's "disastrous" Test and Trace policy.

As head of the Independent Scientific Advisory Group for Emergencies it is shadowing the Prime Minister’s scientific team.

Sir David added: “The government has a month to deal with the level of infectivity as it stands now.

"Reopening schools should be a priority, but we believe we are nowhere near the point where it can be done safely.”

He said the R rate of infection number is expected to rise by about 0.5 with all schools open.

Official government figures released on Friday showed the national rate as between 0.8 and 1 – the tipping point – as infections rise again.

Sir David expressed concern about schools reopening safely

“We need a proper test and trace system by September,” added Sir David.

“Otherwise I’m sure school opening will put us right back.

"We will see the government backing lockdowns and, yes, I do think this could happen nationally.”

He said the Serco tracing contract is up for renewal soon - and they've had £100m roughly so far.

And they will get £300m if it is extended - but he adds that "this is not working."

Sir David King

Instead, he called on the government to hand over control of test and trace to local councils.

"When you hit 3,000 new cases a day, it’s an enormous number for any national body to deal with. But break it down into local regions and the numbers become manageable," he added.

Sir David said the government should follow other countries and put isolating members of multi-generational households in hotels to avoid infecting family members.

But a Department of Health and Social Care spokesperson said: “In just nine weeks NHS Test and Trace has tested over three million people for coronavirus and has reached almost a quarter of a million people who have either tested positive or have been in close contact with someone who has tested positive – in order to break the chain of transmission.

“Specially-trained call handlers work with national and local public health experts, NHS clinicians and local health protection teams, and play a vital role in helping to stop the spread of the virus.”