A briefing sent to Labour MPs from the parliamentary Labour party (PLP) office said that the current position is to oppose in a Commons vote any measures to require people to show proof of vaccination to access shops or pubs.
The government on Monday said vaccine passports could be used by pubs and restaurants to relax social distancing rules, from May 17 at the earliest.
More than 40 Tory MPs have already signed a cross-party letter opposing the idea.
If that many rebelled in a future vote, it could be enough to join forces with Labour an other opposition parties to defeat the prime minister, if he decides to roll out the measures.
Vaccines minister Nadhim Zahawi told Times Radio that “of course we will go to parliament for a vote” if Johnson decides to proceed with passports.
The briefing confirms Labour will vote against the measures, as things stand, as the party believes they will be discriminatory.
It asks the question “how will Labour vote on vaccine and test certification”, before answering: “On the basis of what we’ve seen we would oppose domestic vaccine passports.
“Labour’s focus would be on getting the vaccine out, fixing self-isolation and contact tracing”.
But the party left the door open to backing testing certification that could, for example, allow people to attend large events after a negative Covid test.
Earlier, shadow health secretary Jon Ashworth told the BBC: “I’m not going to support a policy that, here in my Leicester constituency, if someone wants to go into Next or H&M, they have to produce a vaccination certificate on their phone, on an app.
“I think that’s discriminatory.”
A senior Labour source said: “On the basis of what we’ve seen and discussed with ministers, we oppose the government’s plans for domestic vaccine passports.
“They appear poorly thought-through, will put added burdens on business and run the risk of becoming another expensive Whitehall project that gets outsourced to friends of Tory ministers.”
On Monday, a government review said ministers believe “that there are some settings (such as essential public services, public transport and essential shops) where Covid-status certification should never be required, in order to ensure access for all”.
But it added: “Equally, Covid-status certification could potentially play a role in settings such as theatres, nightclubs, and mass events such as festivals or sports events to help manage risks where large numbers of people are brought together in close proximity.
“It is possible that Covid-status certification could also play a role in reducing social distancing requirements in other settings which people tend to visit more frequently, for example in hospitality settings.”