The NHS Test and Trace system provided more than 7,000 people with the wrong dates for the start and end of their self-quarantines, it has been confirmed.

A Department of Health and Social Care spokesman said an error was caused by an internal update to the system’s software and affected 7,230 people.

Once the error was realised 4,775 people were contacted with new advice on when their self-isolation period should end.

But the quarantine periods had already concluded for a further 2,455 individuals who were affected by the glitch.

“We have reassessed the self-isolation periods for a number of people who were contact traced, following close contact with someone who tested positive for Covid-19,” the department’s spokesman said.

It comes a day after the outgoing director of the scheme admitted that testing is “by no means perfect” as she hands over to former Sainsbury’s boss Mike Coupe.

In a thread of tweets, Sarah-Jane Marsh wrote the programme needed to give “even greater control to local systems”, adding that “most of all we need to better communicate that testing is a means to an end not an end (in) itself”.

“It is not the strategy, it enables the strategy, and whilst we have a scaled diagnostic capability to be proud of, testing alone will never be the answer,” she added.

Boris Johnson admitted last month the Test and Trace system needed to improve, after it was revealed that just one in seven people having a test at a centre were getting their result back in 24 hours.

He said he shared people’s “frustrations” with the system and said there needed to be faster turnaround times.

On Monday the UK’s coronavirus testing capacity surpassed 500,000, reaching a target Mr Johnson promised to meet by the end of October.

The latest data on the Government’s coronavirus dashboard shows there is currently a capacity for 519,770 tests, but just 270,473 tests were actually processed.

The Prime Minister described meeting the target as “considerable” and thanked those working on the NHS Test and Trace system.