Boris Johnson has said it may not be feasible to implement coronavirus health certificates until everyone has been offered a vaccine, as publicans criticised his plans.

The Prime Minister said on Thursday that the Government will say more on their possible use in early April, and suggested they could also be based on whether individuals have developed antibodies through infection, as well as vaccinations and negative tests.

But landlords rejected their use after his earlier suggestion it could be up to them to decide whether to screen customers’ certificates on entry, ahead of fresh details emerging of a possible incentive for pubs to adopt the measure.

Mr Johnson also defended his credentials as a “freedom lover” as some lockdown-sceptic Conservative backbenchers prepared to rebel in a Commons vote to extend coronavirus laws for a further six months.

The boss of the Shepherd Neame chain said that making jabs mandatory for entry to pubs is a “fairly poorly thought-out idea”, as trade bodies suggested the idea was “simply unworkable”.

Mr Johnson insisted “no decisions have been taken at all”, saying that there will be an update on the review into their possible use on either April 5 or 12, and said that “whatever happens” the April 12 reopening of pub gardens will be unaffected.

The Prime Minister said that “I do think there is going to be a role for certification”, though it is possible this will be limited to foreign travel.

“There are three basic components. There’s the vaccine, there’s your immunity you might have had after you’ve had Covid and there’s testing – they are three things that could work together,” Mr Johnson told broadcasters during a visit to the Monkey Puzzle Day Nursery in Greenford.

But he acknowledged there are “moral complexities” and “ethical problems” that must be addressed, raising concerns that pregnant women and those with medical reasons cannot be vaccinated.

“You might only be able to implement a thoroughgoing vaccination passport scheme, even if you wanted such a thing, in the context of when absolutely everybody had been offered a vaccine,” Mr Johnson added.

Ministers have insisted that their target of offering all adults a vaccine by the end of July will be met despite the European Union’s threat to control supplies from the continent.

EU leaders will discuss proposals aimed at tightening restrictions on vaccine exports at a virtual European Council summit on Thursday.

Meanwhile, MPs will be asked to approve the regulations for the route out of lockdown and keep some of the emergency powers in the Coronavirus Act in place until September.

Though they are expected to pass comfortably because Labour will not oppose them, the leader of the Covid Recovery Group of lockdown-sceptic Tory MPs was highly critical of the move.

Mark Harper, a former chief whip, said he has not “heard a single good answer about why” the Government wants to extend “very significant draconian powers” for a further six months.

Ahead of the vote, Mr Johnson said: “The libertarian in me is also trying to protect people’s fundamental right to life and their ability to live their lives normally.

“And the only way really to restore that for everybody is for us to beat the disease and the best path to freedom is down the cautious but irreversible road map that we’ve set out – that’s what the freedom lover wants.”

On Wednesday, the Prime Minister said it “may be up to individual publicans” whether they carry out health certificate checks on punters.

Jonathan Neame, the chief executive of Shepherd Neame pub group, ruled out making vaccines mandatory for entry to his premises, warning bar staff could be “subject to intimidation”.

“This is fraught with difficulty, I think, and it is, in my view, a fairly poorly thought out idea at this stage,” he told BBC Radio 4’s Today programme.

Kate Nicholls, the chief executive of the UKHospitality trade body, said the plan is “simply unworkable” and the British Beer and Pub Association said the requirement would not be “appropriate or necessary”.

Cabinet Office minister Michael Gove is reviewing the possible use of coronavirus status certificates under plans to ease England’s lockdown.

The use of certificates may not be as straightforward as vaccine or no vaccine, as recent negative test status may also be considered.

A Whitehall source told the PA news agency that landlords may be able to scrap social distancing if they check Covid health certificates on entry, in a move that would allow them to operate at much higher capacity.

Under the suggestion being considered in the review, those who do not want to enforce the checks would be allowed to reopen but would have to ensure social distancing is maintained.

In Brussels, EU leaders were meeting to discuss tightening vaccine export restrictions as the bloc is embroiled in an enduring row over supply with AstraZeneca.

A joint statement moving to cool tensions said the two sides were seeking a “win-win” deal to increase supplies across the UK and EU.

Government data up to Tuesday showed 28,653,523 people have received a first vaccine dose, a rise of 325,650 on the previous day.

A further 98 people had died within 28 days of testing positive for Covid-19 as of Wednesday, bringing the total by that measure to 126,382.

As of 9am on Wednesday, there had been a further 5,605 lab-confirmed cases in the UK, bringing the total to 4,312,908.