An order has been made for the Welsh government to release more information about how many jobs are being created in its seven enterprise zones.
The information commissioner has given ministers 35 days to publish the data, after a complaint by Plaid Cymru.
The Welsh government can appeal against the decision at a tribunal.
Plaid accused ministers of trying to "avoid scrutiny" and welcomed the commissioner's decision. Ministers said they would respond "in due course".
The dispute follows a freedom of information request by Plaid Cymru, who asked how many jobs had been created in each zone.
More than 5,000 jobs have been created or safeguarded over two years in total, but Plaid has complained that the public has a "right to know more".
Ministers said publishing individual breakdowns for the zones could "prejudice the Welsh government's ambitions in the longer term to deliver the wider economic benefits across Wales".
But Plaid Cymru AM Rhun ap Iorwerth said: "Nearly three years after they were launched the public deserve to be told how many jobs have been created in each of them and how much investment has been made."
The Welsh government launched the first enterprise zones in 2011, bringing together particular types of industries by offering them certain incentives.
The chairs of the enterprise zones have also said the statistics should not be released.
In a letter to Economy Minister Edwina Hart, they said they could "only see the negative impact of the release of sensitive information".
A Welsh government statement said ministers were "considering the information commissioner's decision in detail and would respond in due course.