Michelle O'Neill has reiterated her concerns over the use of 'vaccine passports' in Northern Ireland.
The deputy First Minister said she would 'keep an open mind' as she insisted ministers had yet to reach a formal position on the concept.
Her comments come as the Irish Government introduces rules barring anyone from eating and drinking in indoor hospitality venues unless they can prove they have been vaccinated or have Covid immunity.
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The policy has been cited as a contributory factor in encouraging more young people in the Irish Republic to come forward for jabs.
Stormont officials are examining policy issues around using a vaccine certification system in Northern Ireland.
Speaking in Coalisland, Ms O'Neill said: "On the issue of these domestic certs for access I have issue with those things."
"It's fact to say that the Executive hasn't taken a policy position on that as yet.
"However, the discussions today at the Executive was that health (department) need to look at, if we did get into that point, what would a system like that look like.
"And then we can come back to the policy decision as to whether or not you would use such a system.
"I would be worried in terms of it being a discriminatory system, you know there's a whole lot of human rights concerns and other things that goes with that.
"However, I'll keep an open mind and I'll have the discussion but, for now, health just needs to be prepared for, if we did go there, what would it look like and how would it operate?"
DUP First Minister Paul Givan previously voiced his concerns about domestic vaccine passports.
Last month, Mr Givan said ministers would need to be "cautious" about such a policy, saying it could lead to the exclusion of some people.
