The coronavirus testing system is struggling to keep up with demand as a growing number of people apply for swabs. People with symptoms applying for drive-through tests have been directed more than 100 miles (161km) away. The government says areas with fewer coronavirus cases have had their testing capacity reduced, in order to cope with outbreaks.

A postcode search of the government's coronavirus test booking service reveals:

• People with symptoms living in London are being directed between 50 and 135 miles away, including to testing sites in Cardiff and the Isle of Wight
• A postcode in Devon was directed to a testing centre 109 miles away in Carmarthen
• One in Worthing was directed 40 miles away
• One in Cumbria was sent 50 miles away to Dumfries
• In Sheffield on Wednesday morning the closest available testing centre was 20 miles away
• These distances are the ones that are given on the government website, but they appear to have been calculated as the crow flies, rather than being a true reflection of how long it would take to drive - for example, the Devon to Carmarthen route was actually a 206 mile drive according to Google Maps.

And it's been taking longer for people who do go to a drive-through testing centre to receive their results back, too. NHS Test and Trace figures show in the week of 13-19 August, 41% of in-person tests at mobile testing units and drive-through centres gave results within 24 hours. That's down from 61% the week before.

For all routes combined, including home kits, 20% of tests had results back within 24 hours, compared with 29% the week before.

The government has pledged to increase its capacity to 500,000 tests a day by the end of October. Currently, it says, testing capacity is about 350,000 a day - but only just over half of that is being used. Daily testing has only broken 200,000 on one day, despite the government hailing reaching its target of having that level of capacity at the end of May.

Dido Harding has apologised after test and trace workers directed some people to centres more than 100 miles away from where they live. Harding, head of England’s test and trace system, said she was “very sorry” for the situation but insisted the “vast majority” of people seeking Covid-19 tests were still able to get appointments nearby.

It comes as Health Secretary Matt Hancock defended the Test and Trace scheme as working “well” despite the vast distances some people have been asked travel.

The lack of availability of tests locally, with capacity in some areas being reduced so that tests can be targeted in places where Covid-19 is known to be more widespread, has raised concerns that the system has dangerous flaws that could put people’s health at risk.

A senior test and trace source said a change in the system in England would be going live either on Thursday or Friday to restrict test centre locations to within 75 miles. It is understood there are plans to improve the algorithm so that it suggests suitable locations.

Mr Hancock said difficulties in getting people tested locally was one of the reasons for announced a new £500m funding package aimed at supporting trials of a 20-minute test and efforts to explore the benefits of repeatedly testing people for the virus.

Sarah-Jane Marsh, who works as a deputy to Dido Harding*, heading up the "test" element of the test and trace scheme in England has issued a "heartfelt" apology for problems with the coronavirus testing system.

In a tweet, Ms Marsh explained it was the laboratories, not the testing sites themselves, that were the "critical pinch-point".

"All of our testing sites have capacity, which is why they don't look overcrowded," Ms Marsh explained. Instead, appointments were restricted because of a blockage in processing capacity in the labs.

Health Secretary Matt Hancock said there had been a "a problem with a couple of contracts" which would take a matter of weeks to be "sorted in the short term".

Health Secretary Matt Hancock said increasing numbers of people in England were seeking tests when they didn't have any Covid-19 symptoms. He said this "inappropriate" use of the system was making it harder for people who needed tests to get one.

It comes after the boss of England's testing system apologised to people who were struggling to get tests.

The free tests are available to people with symptoms of coronavirus - a fever, new and continuous cough or a loss or change in sense of taste or smell.Mr Hancock gave the example of one school who sent a whole year group for tests, which is "not appropriate", he added. Mr Hancock also described how some people who were going on holiday had sought to get tests.

Labour's shadow health secretary Jonathan Ashworth said: "It beggars belief that after weeks of encouraging people to have a test if feeling unwell, ministers are seeking to blame people for simply doing what they were advised. With children returning to school and thousands returning to the office, it's obvious extra testing capacity would be needed. The fact ministers failed to plan is yet more staggering incompetence."

Sir Keir says he spoke to a mum In London who had a child with a high temperature yesterday morning, she couldn’t get a test and was told the nearest was Romford, but there was no tests there. She was then told Telford or Inverness was the nearest - but couldn’t get a test there either. At 9pm last night she was told the nearest centre was Swansea. He asks who the PM thinks is responsible for this?

The PM says he takes full responsibility for the handling for the coronavirus crisis, as he has from the start.

12:10 Sir Keir asks who is right - the director of test and trace who says it is a lab problem, or the health secretary who says it is the public’s fault?

The PM says he is sorry to those facing problems getting a test but demand is at an ‘unprecedented high’.

12:21 The PM says Sir Keir is ‘attempting to undermine confidence in test and trace..

Sir Keir says families having to drive hundreds of miles for tests is what’s ‘undermining confidence’. “I just want it fixed, we don’t need to have an argument. “ he says.

12:26 Sir Keir asks the PM when he first knew that people having to drive across the country for tests was a problem.

The PM does not answer.

"Why can’t we just hear from the PM an honest answer", Sir Keir asks. Far from the world beating system we were promised, the government can’t even get the basics right”, he says. When is this problem with test, trace and isolate going to be fixed?”

On 21 July, Hancock tweeted a video of himself speaking in the Commons about the issue, adding the message: “If you have symptoms of #coronavirus, or if you have any doubt, get a coronavirus test. Anybody who needs a test can get a test, & it’s the most important thing that you can do to stop the spread of this virus.”