Dec 28 (Reuters) - U.S. oil major Exxon Mobil Corp (XOM.N) is suing the European Union in a bid to force it to scrap the bloc's new windfall tax on oil groups, arguing Brussels exceeded its legal authority by imposing the levy.Record profits this year by oil companies benefiting from high energy prices have boosted inflation around the world and led to fresh calls to further tax the sector.The windfall profits tax is "counter-productive," discourages investments and undermines investor confidence, Exxon spokesperson Casey Norton said on Wednesday.Exxon will factor in the tax as it considers future multibillion-euro investments in Europe’s energy supply and transition, he said.Windfall profit taxes imposed by Europe could cost at least $2 billion through the end of 2023, Chief Financial Officer Kathryn Mikells said in a call to analysts on Dec. 8."