The Government is consulting on whether to introduce a certification system which could also include details on Covid-19 test results.
But former Cabinet minister David Davis, MP for Haltemprice and Howden in East Yorkshire, has warned the Government against introducing such a scheme.
The senior Tory told MPs: “The impact of this would be discriminatory. Under the law it would be indirectly discriminatory and that is illegal.
“You may well find, it has been said, that black and ethnic minority communities are less inclined to get vaccinated, well that would be indirect discrimination.”
Younger people were also less likely to have the jab and “some people have ethical or religious objections”, he told the Public Administration and Constitutional Affairs Committee.
“There are a variety of good reasons for people not to take a vaccine. I’ve had a vaccine and I think most of the reasons are not ones I would subscribe to.
“But people have that freedom. What this proposal does is, in effect, coerce those people.”
In the UK, anyone who has had a jab receives a vaccination card and the details go in their medical records. It is among countries now considering whether to introduce other ways of showing their status. It's been suggested a passport feature could be added to the existing NHS app.
People could use it to prove they have been vaccinated, or recently tested negative. Culture Secretary Oliver Dowden says Covid "certificates" could be used to help people return to large gatherings such as sports events.
European officials have announced plans for a "Green Digital Certificate". This would allow anyone vaccinated against Covid, or who has tested negative, or recently recovered from the virus, to travel within the EU. Officials hope it will be in place before the summer tourist season.
Mr Davis said that if the Government decided to introduce the certificates it should be prepared to table a new law which would go through the full scrutiny process of both Houses of Parliament, rather than as a piece of secondary legislation.
“If we do this it should be primary legislation because it is so serious,” he said.
The former minister suggested that the move was being pushed by officials in Whitehall who had long backed some form of identity documentation.
“It seems to me that we are creating a permanent solution for a temporary problem,” Mr Davis said.
“We know that Whitehall loves the concept of identity management, loves the concept of having control of this data.”
But it would be “very antagonistic to our national traditions” in Britain, he said.
He also played down the reason for introducing the measures, arguing they were aimed at protecting people who declined the offer of a vaccine rather than society as a whole.
If there were 10 unvaccinated people out of 100 in a pub, “the 90 vaccinated are not going to die” and are “very unlikely” to become seriously ill due to the protection offered by the jabs.
“The people you are protecting are the other non-vaccinated, you are saying to people ‘you can’t go to the pub because you yourself might get infected’ and that’s not actually the job of government, any more than it is to tell me I should not go rock climbing or whatever,” he said.
He added the Government was “very, very confused about the ethical basis of who you are protecting”.
“They are pretending they are protecting the whole population – you are not, you are actually protecting the people who are not vaccinated from themselves, which drives a coach and horses through their philosophical basis.”
Despite his opposition to domestic certificates, Mr Davis did accept there was a case for international vaccine passports.
“I am in favour of an international vaccine passport, that seems to me to be perfectly reasonable because the balance of advantage heavily favours that and the intrusion on the individual’s liberty is much lower,” he said.
Mr Davis's warning as it emerged that care home workers could be legally required to have coronavirus vaccines under plans being considered by the Government.
Meanwhile, Boris Johnson has reflected with Cabinet ministers on “a very dark and difficult year” for the nation on the anniversary of the first lockdown, Downing Street said.
A total of 149,117 deaths have now occurred in the UK where Covid-19 was mentioned on the death certificate, according to the Office for National Statistics.
The most number of deaths to occur on a single day was 1,465 on January 19.
During the first wave of the virus, the daily death toll peaked at 1,459 deaths on April 8.
A No 10 spokesman said: “The PM began Cabinet by reflecting on what he said had been a very dark and difficult year for our country.
“The PM said that we mourn all those we have lost and send our deepest sympathies to their families, friends and loved ones.
“The PM said the last year had also shown the great strengths of the British public, which had demonstrated such resilience and fortitude, and had shown such willingness to work together for a common good.”
The Prime Minister and his Cabinet also were said to have paid tribute to the “extraordinary service” of NHS and social care workers, as well as those in the public sector.
He also praised the “absolutely astonishing achievement” of British scientists and businesses in developing a vaccine and delivering it to half the adult population within a year.