The use of Covid vaccine passports is 'under consideration,' the foreign secretary has suggested.
Dominic Raab refused to rule out that people in the UK could be asked to show they are vaccinated when visiting a pub, restaurant or in other areas of society.
It comes ahead of the Prime Minister's announcement as he is due to set out his 'roadmap' out of the coronavirus lockdown in England on the week beginning February 22.
When asked on Sunday about the prospect of documents being needed domestically, Mr Raab told LBC: "It is something that hasn't been ruled out.
"It's under consideration, but of course you've got to make it workable.
"I think the thing with when I've looked at this [is], whether it's at the international, domestic or local level, you've got to know that the document that is being presented is something you can rely on - that it is an accurate status of the individual.
"So I'm not sure there's a fool-proof answer in the way that sometimes it's presented, but we'll look at all the options."
He also reiterated his comments when asked if it will be put on the agenda at the G7 Summit.
Mr Raab told the BBC's Andrew Marr Show: "We can certainly discuss those things both internationally and domestically, but the reality is you've got to have a workable system, so it’s not something that I think yet is in a place where we can put forward a workable proposition that countries around the world would be able to rely on.
"And the risk of course with anything like that is if you create something which isn't workable, that isn't dependable, it creates a false sense of security and no-one wants to do that."
His comments come after the idea was rubbished by other ministers.
In December, Cabinet Office minister Michael Gove told Sky News: "I certainly am not planning to introduce any vaccine passports, and I don't know anyone else in government who is."
This was after vaccines minister Nadhim Zahawi suggested in November that the government was considering "immunity passports."
But at a press conference last week, Boris Johnson said when quizzed on the idea: "When we're in that different world, which I hope will be as soon as possible, then all kinds of apps and all kinds of possibilities will be open to us."
Latest reports suggest the tier system of coronavirus restrictions is set to be axed when the government's lockdown review and plan is published.
Boris Johnson is also said to have signed off on a three-stage national plan for reopening the economy.
