The government’s coronavirus testing programme is dealing with a backlog of185,000 swabs, with tests being sent to Italy and Germany as local labs are overwhelmed.

Not even a week after the government was forced to apologise for continuing delays to Covid testing, the Department of Health and Social Care insisted on Sunday that the capacity of the NHS test-and-trace system was the highest it had ever been but there was a “significant” demand for tests.

This includes demand from people “who do not have symptoms and are not otherwise eligible”, the DHSC said.

Leaked documents revealed the 185,000 backlog and the fact that tests are being sent to German and Italian laboratories for processing, according to the Sunday Times.

It was meant to be the system that would allow the country to emerge confidently from lockdown. But the development of the NHS tracing system has been characterised by missteps, conflict and frustration behind the scenes.

At the heart of the difficulties have been tensions between central government and local public health officials, or as one insider complained: “There has been control freakery from start to finish by the NHS and the Department of Health.”

Public health officials say systems and protocols to manage so-called “complex cases” involving central and local cooperation, such as the outbreak in Weston-super-Mare, have not yet been fully worked out days before schools start reopening on 1 June.

“I think councils will be told who will need extra help because they are vulnerable in a shielded category, and that’s about it,” the official added, saying there had been difficult meetings between officials from both sides.