Healthcare services are being jeopardised by lack of access to coronavirus testing, hospital bosses in England warned on Tuesday.
NHS Providers, which represents the heads of hospital trusts in the state-run National Health Service, said there were "current capacity problems with the testing regime".
Its chief executive Chris Hopson said the government should prioritise health workers, as shortages of tests had caused a slew of staff absences in major cities.
Patients were also struggling to get tests, compounding delays within the NHS that have worsened since the outbreak began.
"We have now got cases where patients who should be being treated, we can't treat them because they can't get access to a test," he told Sky News television in an interview.
"So, for them that's a real problem."
Hopson spoke after LBC radio reported on Monday that no coronavirus tests were available in any of the 10 worst hotspots in England.
The revelation followed weekend reports of a backlog of 185,000 swab tests, and that the system was so stretched samples were being sent to labs in Italy and Germany.
The UK government has blamed surging demand for the situation and promised increased capacity while urging people only to get tested if they are showing symptoms.
Interior minister Priti Patel denied claims of acute shortages in England's hotspots, saying mobile testing units were boosting capacity in areas under local lockdowns.
"Clearly there is much more work that needs to be undertaken with Public Health England and the actual public health bodies in those particular local areas," she told BBC radio on Tuesday.
Britain, which has been the worst-hit country in Europe registering nearly 42,000 deaths, has seen a resurgence in the virus in recent weeks.
The country recorded more than 3,000 new cases on three consecutive days over the weekend, for the first time since May.
Prime Minister Boris Johnson had pledged to have a "world-beating" testing and tracing operation in place by June.
But alongside the faltering testing regime, the tracing system is still failing to reach the required number of people to work effectively.
Meanwhile, a much-touted smartphone app to help trace people is yet to launch in England.
Scotland, which runs health from the devolved administration in Edinburgh, launched an app last week using technology developed by Apple and Google.
Grumble and grouse over restrictions
British interior minister Priti Patel on Tuesday urged people to comply with new anti-virus rules in England limiting social gatherings to groups of six, encouraging them to report lawbreakers to the police.
But there was consternation that grouse shooting and other hunting with guns would remain exempt, leading to accusations of double standards.
The new restrictions came into force on Monday across England to try to stem a resurgence in coronavirus cases but will not apply to large families, workplaces, weddings and funerals.
The government wants to avoid another nationwide lockdown and boost the flagging economy, even as the number of positive cases climbs to levels not seen since May.
"I think anybody would want to take responsibility and ensure we're not spreading this awful disease and therefore if I saw gatherings of more than six people clearly I would report that," Patel told the BBC.
The government has been accused of overreach by calling on people to tell the authorities about anyone flouting the new law.
The Sun tabloid, which carried a front-page headline "Snitch", said there was "fury at minister's call for rule of 6 snoops".
The national chairman of the Police Federation of England and Wales meanwhile called for more guidance over how officers should enforce the rules.
Prime Minister Boris Johnson's spokesman told reporters Monday that officers would use their discretion before issuing fines.
"In the coming days if we see people continuing to flout the new rules it is right that people could face a fine," he said. "The public will expect them to be enforced."
The new "rule of six" has caused further confusion as to what is allowed, with the government accused of effectively outlawing children's birthday parties.
But the HuffPost said grouse shoots of between six and 30 people were still allowed because it is covered by a loophole that permits licensed "outdoor activity".
Luke Pollard, the main opposition Labour Party's environment spokesman, hit out at exemption for hunting -- a pastime more traditionally supported by Conservative voters.
"Once again, it's one rule for the Cabinet and their mates, and another for the rest of us," he said.
Even some Tory MPs were bemused by the move. Former sports minister Tracey Crouch called it "bonkers".
"Many will find this topsy-turvy prioritisation from government," she told HuffPost.
"I've had queries about choirs, community bands, addiction therapy groups, all of whom would be worthy of an exemption and instead we are scrabbling around prioritising shooting animals."