EC’s investigation found that the Harburg refinery assets in the Hamburg region would be likely to close if there were no agreement to buy them, which would reduce production capacity in the European Economic Area (EEA), leading to higher prices for consumers.

EC vice president in charge of competition policy Joaquin Almunia said if the acquisition does not take place, the Harburg plant would simply close down, reducing production capacity in Europe for a number of specific oil products.

"We authorised this acquisition because it is the only way to avoid a price increase for consumers," Almunia said.

EC claims that upon completion of the transaction, the merged entity will remain the only naphthenic base and process oil producer and the largest producer of TFO in the EEA.

The investigation from EC focused on concerns that the transaction may harm competition from the US-based firm Ergon, which entered the EEA market as an importer in 2008.

The commission said the acquisition has positive effects on competition, as Nynas would achieve significant reductions of variable costs for its additional supplies, which are likely to be passed on to consumers to some extent.