The government has said an app to verify Covid passports will be available "by Saturday" amid confusion over their use three days ahead of reopening.
Official guidance has urged nightclubs and events in England to consider asking customers to show proof of vaccination to enter when restrictions ease on 19 July, but it is unclear how such a system will work.
It is understood an NHS Covid Pass Verifier App will be available for download in app stores by 17 July, alongside full guidance for operators.
Venues can also conduct a visual check of an individual's Covid Pass with security features including an animated shimmer that cannot be screen-grabbed.
A government spokesperson said: "People can demonstrate proof of vaccination, a recent negative test or natural immunity a number of ways, including through the NHS Covid Pass on the app which can be scanned or visually verified. More guidance on using the Covid Pass will be published shortly."
How can people access vaccine passports?
People can get a Covid passport through the NHS app, which is different to the NHS Covid-19 contract tracing app. Anyone aged over 16 who is registered with a GP surgery in England can sign up and click through to a QR code confirming their vaccination status, which lasts for 28 days.
The QR code can also be downloaded as a PDF or sent via email. People can also request a letter confirming their vaccination status through the post.
Some hospitality operators told The Telegraph not all venues would have the technology to scan QR codes to prove vaccination status.
UKHospitality chief executive Kate Nicholls warned any Covid passport system risked creating tension between staff and guests and raised issues around equality laws and customer data.
"For businesses to get back to profitability, it's vital they are able to arrive at solutions that suit their business model without incurring extra costs," she said.