By Veronika Gulyas

BUDAPEST--Another spat between Croatia and Hungary's MOL Central Europe's largest oil and gas firm MOL Nyrt (MOL.BU) suggests any agreement on Croatian refinery INA may be even more distant.

On Monday, Croatian Economy Minister Ivan Vrdoljak claimed MOL "ruined" INA over the years it has been under its management, citing a study. On Tuesday, MOL said the comments hurt INA's reputation and that the study was flawed.

The Croatian government wasn't immediately available to comment Tuesday.

Mr. Vrdoljak was quoted as saying by several media outlets that during the past five years Croatia has "lost several billion dollars," with targets missed and production down.

MOL dismissed the claims and questioned the independence and credibility of the study quoted by the Croatian minister.

"The minister's recent media approach can only be understood as an attempt to deflect attention from his recent regulations, which caused over 1 billion Croatian kuna of damage to INA," Dominic Köfner, Vice President of Corporate Communications at MOL, said in a statement.

To date, MOL has invested a total of 1.4 billion euros ($1.96 billion) directly into the Croatian economy, the company said.

This week's developments mark just the latest step in the ongoing battle between the Croatian government and MOL. Croatia wants to regain control of INA, in which it holds a 44.8% stake following INA's privatization in 2003. MOL owns a 49.1% share of the refinery and its management rights.

The two parties are embroiled in a bribery case in which, in 2012, former Croatian prime minister Ivo Sanader was convicted of accepting bribes while he was in office to allow MOL to have management rights over Croatian peer INA, according to a Croatian court.

MOL has repeatedly said the case was politically motivated and denied all the Croatian allegations. The company said Mr. Hernádi has demonstrated to the MOL board's "full satisfaction" why the allegations are unfounded and why the case is without merit.

Write to Veronika Gulyas at veronika.gulyas@wsj.com