By Kate Abnett BRUSSELS (Reuters) -European Union countries on Tuesday backed the bloc’s plan to impose a world-first carbon dioxide emissions tariff on imports of polluting goods, although the finer details will need to be worked out in upcoming negotiations. The EU wants to introduce CO2 emissions costs from 2026 on imports of steel, cement, fertilisers, aluminium and electricity — a move aimed at protecting European industry from being undercut by cheaper goods made in countries with weaker environmental rules. A three-year transition phase for the levy would begin in 2023, so EU countries…