LISBON (Reuters) -The governments of Portugal and Spain will decree on Tuesday the introduction of a Brussels-backed temporary cap on reference prices of natural gas and coal used by power plants, Portuguese Prime Minister Antonio Costa said on Monday. The European Commission agreed two weeks ago to allow the Iberian nations to initially cap prices at 40 euros per megawatt-hour, with the price limit projected to average out at 50 euros over the coming 12 months. European countries are struggling to manage surging gas and power prices, pushed higher by Russia’s invasion of Ukraine, and to cushi…