Turkey’s statistical institute Monday confirmed it filed a criminal complaint against a group of independent inflation researchers that have been publishing alternative inflation data.

The body said the complaint was over what it sees as an opaque methodology rather than their results, which suggested prices rising more than official data, according to a Bloomberg report, citing documents.

The body has demanded ENAGroup, an independent inflation research group, be fined for “purposefully defaming” the official statistics institution and “misguiding public opinion,” the report noted.

ENAGroup started publishing its own inflation data in September amid claims from opposition lawmakers, who raised questions about the accuracy of official inflation data, arguing that the published rate was lower than the market realities.

“They are obliged to express the scope of the research, sampling method and sample volume, data collection method and application time together with the results of the research,” the Turkish Statistical Institute (TurkStat) said in a statement Monday.

The criminal complaint was filed on Feb. 23, the statistics body said.

The ENAGroup's first published finding in September had suggested that the monthly inflation was more than triple the official rate, noting that consumer prices in the month rose 3.61% from the previous month, compared to TurkStat's calculation of a 0.97% increase.

The group aims to “damage and discredit the Turkish Statistical Institute” by spreading misleading data that are used by opposition parties, Treasury and Finance Minister Lütfi Elvan said last week.

“There’s no such thing as TurkStat playing with numbers or inflation reaching 30%-40%,” the minister said.

Long an issue for the economy, Turkey's annual inflation climbed to 17% in April, its highest level in nearly two years, according to TurkStat data. Month-on-month, consumer prices rose 1.68%.

The Central Bank of the Republic of Turkey (CBRT) in late April raised its year-end inflation expectations to 12.2% from 9.4%.

A model by the ENAGroup suggested April inflation surged 2.62% month-on-month. The group has not yet published a year-on-year figure.

TurkStat said the “content of the criminal complaint is limited to the fact that the relevant group does not publish the necessary explanatory information with their news bulletins.”

“It is not related to the results of the published study and it is also not intended to prevent or stop the studies they have performed,” the statistics body said, urging researchers to avoid presenting their data “in a way that will undermine the trust in official statistics or create a basis for manipulation.”