England has recorded more than 10,000 positive coronavirus tests every day since the middle of last week following an error by public health england, damping hopes that the pandemic was flattening out.

The health agency said late on sunday that it had identified 15,841 positive cases between september 25 and october 2 that it had failed to include in its daily reporting of statistics or pass on to the nhss test and trace system.

Scientists said the mistakes at phe were likely to intensify the upsurge in coronavirus cases because the contacts of those who tested positive were not traced.

Rowland kao, professor of veterinary epidemiology at edinburgh university, said: all those individuals with positive results that were not entered into the system have contacts who remained an infection risk to others over this period and so we can expect that they will have already contributed extra infections which we shall see over the coming week or so.

The revision of the figures contradict the encouraging signs seen in england towards the end of last week. oliver johnson, director of the institute for statistical science at bristol university, said it was now hard to believe an office for national statistics survey that showed the growth in the rate of infection was slowing.

With positive cases rising sharply over the week, he said that although the daily positive case number of 22,961 reported by phe on sunday was an exaggeration, four days at or around 10,000 is plenty bad enough.

In a statement, susan hopkins, joint medical adviser at phe, said that three quarters of the backlog reflected people who tested positive between september 30 and october 2, when their results were not added to the test and trace system.

This issue did not affect people receiving their covid-19 test results and all people who tested positive have received their covid-19 test result in the normal way, she said.

David spiegelhalter, winton professor of statistics at cambridge university, said that it was best not to focus on the 22,961 cases reported late on sunday evening. the big spike from this discovered backlog only goes to emphasise how inappropriate it is to focus on the daily reported count. it would be better to have an accurate idea of what was actually happening a few days ago, he said.

The number of people in englands hospitals being treated for covid-19 also rose 35 per cent in the past week from 1,721 to 2,329, although this was still far below the peak of more than 17,000 in mid-april.

In clearing the backlog of its reported positive cases, phe added more than 1,000 cases to the positive case totals for people who were tested at least a week earlier, undermining the tracing system, which relies on rapid identification of contacts so they can self-isolate and stop onward spread of the virus.

At no other time have so many cases been added late to the governments reporting of the spread of coronavirus.

Although the system has suffered from delays in the past, this was an unprecedented failing with the nhss test and trace mechanism. michael brodie, interim chief executive of phe, said: we fully understand the concern this may cause and further robust measures have been put in place as a result.