Opening schools to more pupils before the contact tracing system is in operation would risk a further spike in the coronavirus pandemic, public health experts have warned.

The intervention comes after the government admitted its smartphone tracing app has been delayed and is now not expected to be ready before primary schools are set to open to pupils from three year groups from 1 June.

Schools pensions secretary Thérèse Coffey today told BBC’s Breakfast that the app would be ready in the “coming weeks” and said no condition had been set for it to be established before primary pupils return.

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This would go against the advice of public health experts, who have said the scheme should be “working” when schools open. 

Speaking to BBC Radio 4‘s Today programme, Greg Fell, director of public health at Sheffield City Council, said: “We’re clear that setting the [test and trace] system up is fundamental to breaking the chain of transmission and to reopening society.”

The government has said that primary pupils in Reception, Year 1 and Year 6 should prepare to return to school from 1 June.

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Asked whether the track and trace system should be in place before schools reopen, Mr Fell said: “We need to have the test and trace system working before we start to fundamentally reopen society, because to not do so gives the virus unchecked opportunities to spread, and that will lead us back to a place that we’ve been before and nobody wants to go back there.”

Lisa McNally, the public health director for Sandwell in the West Midlands, also told the programme that she felt that “if we open up schools to more children before we have an effective contact tracing and testing system in place, then we’re putting people at risk - we’re not doing everything we can to protect people”.

Several directors of public health told the BBC that they had not seen compelling evidence that the app would be ready on time, while contact tracers were apparently frustrated with delays to their training.

This morning, shadow education secretary Rebecca Long-Bailey told Sky News that the government “need to move to test, track and trace before a reopening of schools”.