England’s coronavirus lockdown should not be further lifted until the government’s test and trace system has proven to be “robust and effective”, senior World Health Organisation (WHO) official has warned.

Speaking ahead of the reopening of non-essential shops on Monday, the WHO’s regional European director Hans Kluge cautioned against rushing into restarting the economy while the country remains in a ”very active phase of the pandemic”.

“We know that early lockdowns saved lives and bought some time for the health system to be ready,” he told The Guardian. “The question of lifting the lockdown is as important as going to the lockdown. The key words here are to do it gradually. Do it carefully.

He added: “Contact tracing is key especially as the UK starts to relax the social and physical distancing measures. There has to be a robust track-and-trace system in place of operation.”

The tracing system has been repeatedly touted as a key element of the nation’s emergence from lockdown after the UK reported some of the highest rates of infection and death from the virus worldwide.

However criticism has surrounded the system – with an app that had been scheduled to be rolled out with the policy sidelined and contact tracers reporting they had received little or no work since the scheme was launched at the end of last month.

In its first week of operation, the UK test and trace system identified nearly 32,000 people who had been in close contact with someone who had tested positive for Covid-19 – but the government has admitted that the system is not perfect and would need to do better.

The UK recorded a further 36 deaths from coronavirus on Sunday, taking the total to 41,698. The total is among the highest of any country in the world, but the daily toll is the UK’s lowest since lockdown began.

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  Matt Hancock has no idea when contact-tracing app will be ready

It comes as the government looks to review the two-metre social distancing rule implemented to contain the spread of the virus amid concern it will leave hospitality operations unable to function.

Additional reporting by Reuters