Keir Starmer has warned the coronavirus test-and-trace system is “on the verge of collapse”, as ministers conceded that a lack of laboratory capacity which has prevented many people getting a test could take a fortnight to be resolved. The hold-up in processing Covid results, which has seen some people asked to travel from London to Scotland for tests, prompted alarm from council leaders who said it could be calamitous in the period that pupils and students return to education. With some care homes also warning about a lack of tests for staff and residents, the London mayor, Sadiq Khan, urged the government to get a grip, saying the country faced “a critical moment” in avoiding a full-scale resurgence in the virus. Addressing the weekly cabinet meeting on Tuesday morning, Boris Johnson reiterated warnings for young people to socially distance after daily infection numbers shot up to nearly 3,000 for two consecutive days. While the latest daily UK total, released later on Tuesday, fell slightly to just over 2,400, ministers announced new measures in Bolton following a surge in infections including restaurants and pubs being restricted to takeaways. But efforts to prevent the UK following countries such as Spain and France in experiencing wider growth in cases risk being scuppered by persistent problems with the test-and-trace system. After several days in which people reported being told the only available test was hundreds of miles away, or being unable to get one at all, a senior NHS official issued a “heartfelt” apology on Tuesday morning. Sarah-Jane Marsh, the director of testing, tweeted: “All of our testing sites have capacity, which is why they don’t look overcrowded, it’s our laboratory processing that is the critical pinch-point. We are doing all we can to expand quickly.” Prof Alan McNally, who helped set up the Milton Keynes Lighthouse Lab, one of three “megalabs” created to support the testing initiative, called on ministers to clarify the problems labs face. “If we have genuinely hit the peak of what we can handle in terms of requests for tests, then make that public and issue a call to arms to labs to help in any way they can,” he said. “Clearly we are looking at the beginning of another exponential increase in virus cases and the beginning of another large epidemic wave. Everything I’m looking at at the moment points towards that.” Sir Chris Ham, former chief executive of the Kings Fund, said something appeared to have gone “badly wrong” at the Lighthouse labs in recent days. “This is a real canary in the mine moment for us as we begin to approach autumn and winter, that the numbers are moving absolutely in the wrong direction,” he said. Answering questions from the Commons health and social care committee, the health secretary, Matt Hancock, said there had been “operational issues” connected to contracts to carry out tests, adding: “It’s a matter of a couple of weeks until we can get all of that sorted in the short term.” Hancock highlighted that the government had moved to ensure that no one had to travel more than 75 miles for a test, but conceded: “I appreciate 75 miles is far longer than you’d want to go.” Starmer said that while he accepted the full return of schools would bring some risks of higher infection levels, ministers should have got the testing system properly operational beforehand. “What we’re now seeing is stories over the past few days that is showing the testing regime is on the verge of collapse,” he told the BBC. “Heartbreaking stories from people who need a test being told no tests are available, or the website is crashing, or people are being told to go miles and miles for a test. Nobody can argue that that is good governance.” In a parallel warning, Khan said the government risked squandering its “window of opportunity over the summer” to put in place an effective test-and-trace system before schools and universities returned, and questioned why ministers were still focused on encouraging workers back to offices. “To prevent this turning into a tragic second wave of Covid deaths, the government need to urgently get a grip on the test-and-trace system and level with the public about the severity of the situation,” Khan said. “Sending out confusing mixed messages and berating people into returning to the office is the wrong approach approach given the current state of the virus.” Another Labour local leader, Danny Thorpe, who heads Greenwich council in south-east London, said he was still waiting to be told by central government why many locals were first asked to go to Dundee, Leicester or Cardiff for tests, or told none were available. “Government incompetence is going to cost lives,” he said. “It’s a week where we as a council have been flat out getting kids back to school, supporting local businesses and working with local universities and colleges, and for them to be asleep on the job is unforgivable.” Teaching unions also warned that delays in testing could hamper the return of schools, with students and teachers who would test negative staying off unnecessarily. Paul Whiteman, general secretary of the National Association of Head Teachers (NAHT), said: “The government assured us that this would be ready, but at the first sign of stress it seems to be falling over. This will put the successful and sustainable return to school at serious risk. “It is unacceptable for this to happen when schools have put so much effort into getting their part of the plan right, and when pupils have had to endure so much uncertainty and disruption already.” There are also worries that care homes in many areas are unable to have the mandated weekly testing for staff, and monthly tests for residents. Nadra Ahmed, the chair of National Care Association, which represents many care homes, said many members had been in touch over a lack of tests or delays in receiving results. “They are worried,” she said. “It does seem to be almost like a postcode lottery at the moment, which is even more alarming, because outbreaks may not be picked up. By now we were supposed to be doing daily testing by now.” Addressing the Commons on Tuesday afternoon, Hancock stressed that the government was working “flat out” to expand testing capacity. Referencing the worsening situation in Spain and France, Hancock also warned that the virus remains a threat. “This is not over. Just because we have come through one peak, it doesn’t mean we can’t see another one coming towards our shores,” he said.