The NHS Test and Trace system has made no difference to the spread of coronavirus in the UK, an Oxford University scientist has warned.

James Naismith, professor of structural biology, said the system was only reaching a fraction of the number of people who should be contacted.

He told the BBC Radio 4 Today programme: "It hasn’t been effective at all.

"The only ways we are currently able to control infection spreading are social restrictions.

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"Tracking and tracing hasn’t really made any difference to the spread of the epidemic."

He added: “Testing is really important.

"The problem is that if you just look at the number of cases in the UK for the last week you would estimate about 350,000 cases of actual people infected; the testing system only identified just under half of them.

“The point of the system is you need to get a large number of the contacts and break the chains of transmission at a large scale for the Track and Trace system to be effective.

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“Given that you miss over half right at the start and then as you walk through the various losses through the system you are actually reaching 20 per cent of the contacts you want to reach overall.

“Given where we are now in infections, it is not until we get proper mass testing that the system can really recover.”