Plaid Cymru has called on the Welsh Government to release the findings of an exercise into the impact of a hypothetical flu pandemic.
Exercise Cygnus was a three-day event in 2016, which led to a series of recommendations, including some on personal protective equipment (PPE).
The Welsh Government confirmed it took part in the operation and said it led to a UK-wide review of preparedness.
However, the UK government has not published the findings.
Plaid Cymru leader Adam Price said people needed to know what actions "the Welsh Government took to better plan and prepare our NHS for an inevitable pandemic" after the exercise.
It comes after Labour's Shadow Health Secretary Jonathan Ashworth called on the UK government in April to publish the information.
Mr Price said "the public deserve and need to know what happened in this test so that we can learn lessons to help us now".
He added: "This is not just interesting to the public.
"It is in the public interest to know what steps the Welsh Government took in terms of PPE, testing infrastructure, key equipment and their general preparedness for a global pandemic."
The Welsh Government said: "We and other Welsh public bodies were involved in Exercise Cygnus, following which the UK government established a UK review of our pandemic preparedness.
"Some of the review work has fed into the response to this outbreak, such as the emergency legislation."