A number of Conservative MPs have reportedly cast doubt on government plans to introduce vaccine passports for certain events or venues.
Boris Johnson has previously said that from the end of September, people will need to be double jabbed to go to nightclubs, and it has also been suggested that full vaccination will be required for music and sports events as well as university settings.
The plans have sparked protests from people who say the government's plans, along with mask mandates and business restrictions, are overly restrictive.
But Tory MPs have reportedly told Sky News that they do not think the government will push plans to introduce domestic vaccine passports through.
According to campaign group Big Brother Watch, more than 40 Conservatives are among signatories of a campaign to stop the introduction of COVID passports.
Sir Graham Brady, chairman of the 1922 Committee of backbench Conservatives, told Sky News that vaccine passports for domestic use would be a "massive step and a misguided one".
He said: "The policy would discriminate against the young, against those who have medical or ethical reasons why they can't be vaccinated and many ethnic minority groups."
"Fundamentally, people's decision on whether to be vaccinated or not must be a personal decision for them to make based on their own assessment of the benefits and risks."
Watch: Number of Conservative MPs say they think PM won't follow through with vaccine passports
Some MPs reportedly said they think Johnson is bluffing to try to increase uptake of the coronavirus vaccine, while others think the government will back down at the prospect of losing a vote on the issue.
Wellingborough MP Peter Bone said fellow Conservatives were "quite horrified" about the prospect and a "significant number" would vote against the government, while another senior Tory MP said there was an "almost universal objection" in the parliamentary party to vaccine passports.
A government spokesperson told Sky News: "There has been no change to our plans to introduce vaccine certification in September.
"The government is focussed on protecting the public and reducing the impact of the virus, including mandating COVID certification in certain settings.
"Vaccines are the best possible way to protect you and your family against the virus and we strongly encourage people to come forward."
Watch: Do coronavirus vaccines affect fertility?