Repsol may have offered additional discounts at its petrol stations between March and December 2022 while raising wholesale prices for rivals such as independent petrol stations, the CNMC, as the watchdog is known, said in a statement.

This practice “would have had the ability to erode the commercial margins of those competitors and limit competition in retail distribution,” it added.

The watchdog said it opened the probe against Spain’s second biggest oil company after complaints were filed by two associations representing independent fuel station operators.

Repsol “categorically rejects” the accusations, a company spokesman said, adding the firm “scrupulously respects the rules of competition” in Spain.

The discounts were put in place “to help consumers” in the face of price increases caused by Russia’s invasion of Ukraine, he added.

The watchdog has already opened investigations into Cepsa, Spain’s second-largest oil company, and British energy giant BP on suspicion they carried out similar anti-competitive practices in the energy market.