COVID passports could be introduced as a way of ensuring people can get "back to doing the things they love", the culture secretary has said.
Oliver Dowden made the comments as more than 70 MPs sent a warning shot to Prime Minister Boris Johnson by forming a major cross-party campaign against the use of such passports within the UK.
Mr Dowden said cabinet minister Michael Gove is conducting a review into whether "we could make a COVID status certification work".
He said the move could help get more people into places such as theatres.
The culture secretary said: "So this is not about a vaccine passport, it's about looking at ways of proving you're COVID-secure whether you've had a test or had the vaccine.
"Clearly no decisions have been made on that because we have to weigh up the different factors, the ethical considerations and so on, but it may be way of be ensuring you can get more people back doing the things they love."
Conservative MP Tobias Ellwood later told Sky News: "I think Number 10 is going to drop this because a lot of voices from across the political picture have said this is not going to work.
"Internationally it does make sense... but domestically this would be going in the wrong direction."
The prime minister had previously said there will "definitely" be a role for COVID passports for Britons heading abroad, with it reported ministers are discussing a new traffic-light scheme for prioritising travel to countries with high vaccination rates.
But the government is also considering the possible domestic use of COVID certification to help with the reopening of some sectors of the economy after lockdown, as well as reduce the need for social distancing.
Mr Johnson has suggested someone's vaccination status, their possible immunity after having recovered from coronavirus, or a negative test could be part of such a proposal.
He has even suggested the idea of individual landlords being able to decide whether to enforce the use of COVID certification in their pubs - leading to the idea being dubbed a "papers for the pub" scheme.
The Daily Telegraph reported COVID passports are set to be trialled within weeks at pilot events - such as the FA Cup Final, the World Snooker Championships and possibly the Brit Awards - with attendees asked to take a coronavirus test both before and after.
The passports could also be needed for events such as the Bristol Harbour Festival which usually attracts around a quarter of a million people.
One member of the pubic in Bristol told Sky News: "I have had both my vaccines and it would be nice to feel that you are safe somewhere."
Another member of the public in the city said: "If you have to do it you have to do it.
"But I can see the kids are going to download something off the internet, the same as they used to get into nightclubs underage. I think that will still go on."
Amid mounting concerns at Westminster about the possible use of COVID certification, a cross-party group of politicians has signed a pledge to oppose the move.
Their action - in a week when Labour leader Sir Keir Starmer has suggested the "British instinct" will be against the introduction of passports for venues such as pubs - suggests Mr Johnson could face a battle in trying to get plans for COVID certification through the House of Commons.
The signatories to the pledge include leading Tory COVID rebels such as Mark Harper and Steve Baker, who run the COVID Recovery Group (CRG) of Conservative MPs, ex-Tory leader Sir Iain Duncan Smith and former cabinet ministers Esther McVey, Andrew Mitchell and Sir John Redwood.
A 20-strong group of Labour MPs has signed the pledge, including former shadow home secretary Diane Abbott and ex-shadow chancellor John McDonnell.
Labour peer Baroness Shami Chakrabarti and ex-Labour leader Jeremy Corbyn, who now sits as an independent MP, have also joined the campaign.
"International travel is a luxury but participating in your own community is a fundamental right," said Baroness Chakrabarti, who used to run civil liberties and human rights group Liberty.
"So internal COVID passports are an authoritarian step too far."
Almost all Liberal Democrat MPs have signed the pledge, with their party leader Sir Ed Davey having this week branded the use of COVID passports within the UK as "illiberal" and "unworkable".