Less than half of those whose details have been handed to the NHS test and trace scheme because they are at risk of coronavirus have been contacted, leaked documents suggest.
The system launched last Thursday, with 25,000 contact tracers recruited in a bid to prevent the spread of Covid-19.
Since then, there have been claims that many have been left with nothing to do, with the Health Secretary saying that it was right that the system had “more capacity than we need” so it could respond quickly.
On Tuesday night a leaked report on the operation of the scheme up until Sunday showed that 4,456 confirmed cases had been reported to test and trace.
Of those, just 1,831 had filled in a form providing information about their contacts, with 4,634 names handed over.
Just 1,749 had been contacted, according to the report seen by Channel 4 news.
Under the system, anyone with symptoms of coronavirus is asked to immediately book a test.
If found positive, they are asked to hand over details of anyone with whom they have had close contact. These people will then receive a text, email or phone call telling them to enter self-isolation for up to 14 days - and to book their own test if symptoms develop.
The Department of Health and Social Care (DHSC) said the figures were “outdated” but last night refused to provide up to date data.
Hours earlier, Health Secretary Matt Hancock had already been rebuked by the UK's statistics watchdog over coronavirus testing figures for providing inadequate data on testing, meaning that it was “widely criticised and often mistrusted.
UK Statistics Authority chairman Sir David Norgrove said the data published by Government was "still far from complete and comprehensible". He criticised the way the figures are presented at the daily Downing Street briefings, with the headline total including not only the tests carried out, but also those which have been posted out for home testing, but not yet conducted.
On Sunday ministers boasted that they had hit a target to have capacity for 200,000 tests a day early.
But Sir David said: "The testing statistics still fall well short of its expectations. It is not surprising that given their inadequacy data on testing are so widely criticised and often mistrusted."
Widespread computer failures on the day test and trace was launched meant many contacted tracers were locked out of the computer system that showed them the numbers they had to call.
Staff - some of whom started work last Thursday - told The Telegraph they had still not made a single call.
Experts have repeatedly warned that unless contacts are reached quickly, the scheme will make little difference. Last week modelling for the Scientific Advisory Group on Emergencies (SAGE) warned that even a three day turnaround from testing a person to tracking down their contacts would only cut infection rates by 15 per cent.
A spokesman for the DHSC said the figures in the leaked report were out of date.
But officials refused to provide more up to date information.
A spokesman said: “These figures are outdated and fail to reflect the huge amount of work already underway, with thousands of people already contacted in just a matter of days and their contacts successfully traced. We are working with the UKSA to finalise the most useful information to publish on its performance and will be providing weekly updates shortly.”