Scientists advising the UK government believe the planned new Covid restrictions do not go far enough and that “fringe” anti-lockdown epidemiologists are gaining too much attention, the Guardian has learned. Members of the Scientific Advisory Group for Emergencies (Sage) believe that a potential shutdown of pubs and restaurants in the north and Midlands, which is expected next week after delays that one MP has called “reckless”, are unlikely to bring cases down to a more manageable level. Speaking anonymously, some of the experts maintained that a circuit breaker-style intervention of the type being imposed in Scotland from Friday should have been enacted in England two or three weeks ago when such a move was discussed with ministers. This would have involved a two-week shutdown for hospitality venues and other parts of society to drive down cases and hospital admissions. With the UK recording more than 17,500 new Covid-19 infections on Thursday, up almost 25% on the day before, and leaders in northern England in open revolt over imminent lockdown plans, some scientists believe more should have been done already. One senior scientist said the UK was at a critical point and that deeper measures were needed to bring the resurgence under control. Another epidemiologist, Prof John Edmunds, who sits on Sage, said a circuit breaker was needed to prevent the health service from becoming overwhelmed. “The epidemic is increasing and widely,” Edmunds said. “It is, of course, more severe in the north and north-west but it is increasing everywhere and so we have to take action unless we want to face really large numbers of hospitalisations in the quite near term and, unfortunately, large numbers of deaths. This is still a killer virus, despite improvements in treatment.” There is also worry within Sage about the influence of a relatively small number of public health academics who oppose new lockdown moves, with some members understood to be annoyed at the level of coverage they have received. This week thousands of advocates for the Great Barrington declaration urged governments in the UK, US and elsewhere to abandon strategies to suppress the virus and instead let the infection spread among the healthy while protecting the vulnerable. It is unclear how the vulnerable would be identified and protected, and whether allowing the epidemic to grow unchecked in healthy people would lead to the kind of so-called herd immunity that its authors hope would protect everyone. “I can’t see where the evidence is to back it up,” the senior scientist said. Concern about the government’s ability to rein in the spread of coronavirus in coming weeks has been prompted in part by uncertainty over what new measures will be introduced and when. The Guardian understands that the majority of northern England, from Barrow in Cumbria to Merseyside, Greater Manchester, much of Lancashire and Yorkshire and most of the north-east, as well as Nottinghamshire in the Midlands, expects to be under Covid restrictions as part of a new three-tier alert system whose announcement was originally expected this week. On Thursday a government source said the plan was now to make the announcement on Monday, with the measures coming into force on Wednesday. MPs from the affected areas were summoned for a video briefing on Thursday with the health minister Edward Argar and Chris Whitty, the chief medical officer for England. The briefing warned that the number of Covid patients in intensive care in the north of England would surpass the April peak if infections continued rising at the current rate. MPs were also shown early Public Health England research suggesting that bars, pubs and restaurants account for 41% of cases in which two or more under-30s had visited the same venue in the week before testing positive. This fell to a quarter of infections across all age groups. One of the MPs later expressed their frustration. “We got some interesting data but questions about policy were banned,” said Lilian Greenwood, the Labour member for Nottingham South. On Thursday Nottingham had the UK’s highest Covid infection rate, at 689 cases per 100,000 people. “I asked how the science supported delaying extra restrictions in Nottingham until next Wednesday, especially now they’ve been announced to the media so everyone knows this is their last weekend to meet friends and family indoors. “Unsurprisingly, I got a hopeless answer. A load of waffle and excuses about ‘there are lots of things to take into consideration’, ‘regulations take time’ and ‘that’s a decision for ministers’ – the ones who won’t answer questions. I’m fuming, it’s reckless.” Another complication is an expected package of support for businesses affected by the new restrictions, expected to be announced by Rishi Sunak, the chancellor, most likely a day after the measures are announced. Treasury sources said Sunak had drawn up a menu of options over the summer and acknowledged that the job support scheme, which was the centrepiece of his winter economic plan announced a fortnight ago, would not be adequate for areas where an entire sector was being shut down. Allies of Sunak denied he had held up the introduction of new lockdowns, insisting he was keen to give businesses clarity about what new rules they would face.