South Korea says the Korean subsidiary of Fiat Chrysler Automobiles has manipulated exhaust gas levels of two of its models sold in the Korean market.

The Environment Ministry said Monday that it has nullified certification for some two-thousand-400 units of the Italian-American automaker's Jeep Renegade and Fiat 500X SUVs, and plans to impose a fine of three billion won.

The vehicles in question are over one-thousand-600 Jeep Renegade units sold between March 2015 and July 2016 and some 800 Fiat 500X units sold between April 2015 and June 2017. 

The ministry said the automaker either suspended or limited operation of the exhaust gas recirculation system of the models designed to reduce nitrogen oxide emissions.

After conducting various tests between October last year and November this year, the ministry found nitrogen oxide emissions of the rigged Jeep Renegade exceeded the government standard by up to nearly nine times.