Hundreds of pubs could shut for ever unless Boris Johnson decides in the next 48 hours when they can reopen, the UK’s largest beer companies have warned. In an open letter to the prime minister, more than 50 companies said plummeting beer sales and prolonged uncertainty had brought the pub and brewing industry to “a moment of maximum jeopardy” that could cost hundreds of thousands of jobs. The signatories – from global giants such as the Guinness owner Diageo to family brewers such as Adnam’s – urged Johnson to say by Friday whether the government would allow pubs to reopen from 4 July. The date was initially proposed by the government as part of a phased lifting of lockdown restrictions that including permission for non-essential shops to start trading this week. But the prime minister has yet to confirm whether the plan will proceed, despite repeated calls for clarity from the industry, which claims it needs three weeks to prepare. “Our businesses cannot afford to continue in limbo,” the firms, including Carlsberg, Molson Coors and Greene King, told Johnson. “The livelihoods of thousands of publicans and hundreds of thousands of pub and brewery employees in every corner of the UK hang in the balance. “We want to work with the government to get our breweries and pubs back on their feet, but we need urgent clarity from you in order to do this.” As well as confirmation of a reopening date, the letter – coordinated by the British Beer and Pubs Association (BBPA) – calls on the government to publish specific industry guidance that employers can use to train staff. The BBPA said some firms had begun taking staff out of furlough to prepare, while brewers had started making beer to be ready for the return of demand. This had led to increased costs for an industry already burning through £100m a month to sustain itself in the absence of any trade, the BBPA said. The letter represents an escalation of pressure on the government from the beer and pubs industry, which has been devastated by three months of lockdown. Government officials hinted this month that English beer gardens may be able to reopen on 22 June, allowing pubs with outdoor space to start racking up much-needed sales earlier than thought. But Downing Street ditched the plan, fuelling confusion in the industry about reopening and raising fears that many of the UK’s 47,000 pubs may not survive the pandemic. The Guardian has approached Downing Street and the Department for Business, Energy and Industrial Strategy for comment.