Boris Johnson faces a battle over plans to introduce “vaccine passports” for people to demonstrate their Covid-19 status before going to events.

A Government review into “Covid status certification” found they could “potentially play a role” in settings such as theatres, nightclubs and mass events, and might also be used in pubs and restaurants to reduce social distancing restrictions.

The potential use of certificates – which would include vaccination status, test results or evidence of someone having contracted and recovered from Covid-19 – is opposed by at least 40 Conservative MPs and Labour is also sceptical about the measure.

The row over vaccine passports came as the Government’s scientific advisers warned that further steps along the road map to ease England’s lockdown could result in another wave of coronavirus cases.

The next stage of the process – on April 12 – will see non-essential shops, pub beer gardens and hairdressers among the businesses allowed to reopen.

Minutes of a March 31 meeting of the Scientific Advisory Group for Emergencies (Sage) showed that modelling suggested the measures “may only lead to a modest increase in hospitalisations and deaths” and were “unlikely to exert pressure on the NHS”.

But the advisers warned that changes planned for May and June – when greater indoor social mixing is set to be permitted again – could cause hospital admissions to rise to levels seen during January’s peak, according to scenarios based on “pessimistic but plausible” assumptions about how effective vaccines will be.

Covid status certificates are being examined by a panel led by Cabinet Office minister Michael Gove as a way of allowing society to return to normal while minimising the risk of another wave of cases.

The Prime Minister has stressed that the Government has not finalised any plans but ministers are concerned that if there is not an official certificate then firms might require customers to demonstrate if they have had a vaccine or test anyway.

Vaccines minister Nadhim Zahawi acknowledged the use of coronavirus certificates domestically raised difficult ethical questions.

He told Times Radio: “We haven’t even got to the stage where we have decided what we want to do on this domestically, because there are so many issues that do need careful consideration.

“Michael Gove is consulting with all stakeholders, including Parliamentarians, so we are not there yet.

“But the Prime Minister made it very clear, if we do get to that place, then of course we will go to Parliament for a vote.”

Any vote could be close, given the scale of Tory opposition and Labour’s reservations about the policy – which Sir Keir Starmer said would be against the “British instinct”.

Shadow health secretary Jonathan Ashworth told BBC Breakfast that Labour was “very sceptical” and wanted more details about how they would work.

The interim findings of the Government’s review said public transport and essential shops would not require vaccine passports.

But Mr Ashworth said: “I’m not going to support a policy that, here in my Leicester constituency, if someone wants to go into Next or H&M, they have to produce a vaccination certificate on their phone, on an app.

“I think that’s discriminatory.”

He said while it “makes sense” to ask people to take a test before going to events such as football games “we don’t think asking you to produce a vaccination passport, which is this digital ID card, is fair”.

“It’s discriminatory,” he said.

The plan faces opposition from MPs ranging from Labour ex-leader Jeremy Corbyn to the chairman of the powerful Tory backbench 1922 Committee Sir Graham Brady.

Senior Tory Mark Harper, chairman of the lockdown-sceptic Covid Recovery Group, warned Covid status certification “will lead to a two-tier Britain”.

Covid status certificates would not be introduced until later in the year as England proceeds along Mr Johnson’s road map which could see restrictions largely lifted by late June.

A paper from modelling experts at the London School of Hygiene and Tropical Medicine (LSHTM) said their projections suggested stage four – pencilled in for June 21, when remaining restrictions are expected to be abolished – could “lead to a larger surge of cases and deaths comparable to that seen during the first wave”.

They cautioned their findings were “preliminary” and made “pessimistic assumptions” about the later stages of the road map.

But scientists at the University of Warwick also shared a similar conclusion that a “distinct third wave of infection” would arise due to the current rate of planned unlocking, with hospital admissions peaking between late July and mid-August.

Professor Graham Medley from the LSHTM, chairman of the Scientific Pandemic Influenza Group on Modelling (Spi-M), which advises the Government, told BBC Radio 4’s Today programme a third wave could result in more deaths.

He said the three independent models published by Sage – LSHTM, Warwick and Imperial College London – “show that, as we open up, as the virus starts to transmit some more, and because the vaccine isn’t 100% safe, then it’s almost inevitable that we will see some increase in infections, and potentially hospitalisations and deaths”.

He said the LSHTM modelling was “quite a pessimistic view” but “it is plausible, it’s not extreme”.