Nicola Sturgeon has accused Boris Johnson of ignoring expert advice about the need for a Covid restrictions strategy that includes an “extreme” top level close to the full lockdown imposed in March. Sturgeon confirmed she would announce a five-tier system of restrictions on Friday that will partly mirror England’s three-tier traffic light system of controls, as Scotland’s Covid-19 infections and fatalities climbed sharply to levels not seen since May. She said the Scottish system would start with a zero-level tier “which is the closest to normality we can reasonably expect to live with until we have a vaccine or a more effective treatment for this virus”. After confirming Scotland had passed the 50,000 infections threshold overnight, with 28 new fatalities, the first minister said her government had heeded warnings from England’s chief medical officer, Prof Chris Whitty, that a very tough top tier of controls was needed in extreme situations. “The English system starts at medium, which is quite a high level of restriction,” she said. “We also think we need another one at the top because if you remember when England published theirs, the chief medical officer in England said he thought that the top level was not enough to necessarily get the virus down. “We think we need one above that which is not identical to but perhaps closer to a full lockdown, if things got to be that serious.” The first minister said temporary restrictions affecting millions of people across central Scotland, including the closure of pubs and cafes that serve alcohol, and a ban on contact sports and outdoor live events, would remain until the five-tier system starts on 2 November. Business leaders and hospitality firms are furious, arguing it will lead to thousands of job losses. They say the Scottish government’s emergency grants are inadequate, comparing badly with those offered to English councils. Sturgeon refused to set out what each tier would involve in advance of Friday’s announcement but confirmed strict travel restrictions would be included at higher levels, while schools would not automatically close if the top tier was imposed. Sturgeon said Ireland and New Zealand were among countries with five-tier systems; Ireland went to its top tier earlier this week, but the New Zealand government website shows it actually has a four-level alert system. Scotland’s new alert system will be implemented to coincide with council boundaries, and could flex up from regional level to national level if needed. “We need to apply those tiers in a sensible way with allowing people to live with as proportionate and as targeted a set of interventions as is possible at any given time,” she said. Stephen Montgomery, a hotelier in Glasgow who represents the Scottish Hospitality Group, an umbrella body for pub and hotel chains that employ about 6,000 staff in total, said many of the 17,000 businesses affected by the restrictions in central Scotland may no longer be viable. The UK government furlough scheme would end next week but the ban on pubs opening would continue, leaving firms unable to keep on staff. Scottish government funding of £40m compared badly with the tens of millions offered to English cities, he said. “Recent restrictions were framed as a ‘temporary’ short, sharp shock, but the extension is an indication that we can only expect a continued government stranglehold on hospitality that will have devastating consequences,” he said.