Fuel suppliers said on Friday that gasoline sold locally meets regulatory requirements following a complaint filed by Honda Motor Co’s Pakistan subsidiary accusing suppliers of adding a manganese-based additive to improve the octane rating.

Honda Atlas Cars (Pakistan) Ltd., filed the complaint with Oil & Gas Regulatory Authority (OGRA), saying the additive appeared to be damaging engines in its vehicles.

“Fuel being sold in the country is strictly in accordance with the approved specifications issued by the Ministry of Energy, Petroleum Division,” a body representing Pakistan’s fuel suppliers said in a statement.

“The question of sale of poor quality fuel does not arise,” the statement issued by Pakistan’s Oil Companies Advisory Council (OCAC) added.

The Honda complaint, a copy of which was seen by Reuters, said tests found dangerous levels of manganese in fuel samples from Shell Pakistan Ltd, Total Parco Pakistan Ltd and Pakistan State Oil Company Ltd (PSO).

The tests showed levels of manganese of up to 53 milligrams per kilogram (mg/kg), while the additive is deemed to be at a “danger level” at 24 mg/kg, the Honda complaint said. Pakistan’s Oil and Gas Regulatory Authority (OGRA) said on Thursday that it would investigate the complaint filed by Honda .

A senior industry executive told Reuters that Toyota’s Pakistan subsidiary Indus Motor Company was also concerned about manganese levels in gasoline .

“Now that Honda has formally complained they may also follow suit,” the official said, asking not to be identified.