Brussels - The energy issue, with the so-called Third Package, will be one of the main items on the agenda at the E.U.-Russia energy summit to be held in Brussels on Thursday, as announced by Russia's Permanent Representative at the European Union, Vladimir Chizhov. "The energy sector is an important area in our relations," he explained, "and has become the first dialogue at an industrial level debated between Russia and the EU". Simultaneously, added the Russian diplomat during a press conference in Brussels, "we still have not agreed on a number of points, including the Third Energy Package." "A number of countries," reported Chizhov ," have chosen the less flexible option in applying the Third Package's measures". In the diplomat's opinion, "this goes against the principles of EU-Russian relations." The most controversial aspect debated between Russia and the EU concerns legislation on "unbundling", hence the separation of production and distribution activities. The EU wants member states with a "vertically integrated" transport-transfer system to choose by March 2012 a system for guaranteeing the independence of transporters. This will directly affect the the oil company that is most "vertically integrated", the Russian energy giant Gazprom, responsible in various EU countries both for the production and transport of natural gas.