Ukrainian President Petro Poroshenko and European Commissioner on European Neighborhood Policy and Enlargement Johannes Hahn during a telephone conversation have discussed strengthening the energy security in Europe.

"The head of state stressed that the European Commission's decision to expand Gazprom's access to the OPAL gas pipeline goes against to the spirit of the Association Agreement between Ukraine and the EU and the Energy Community Treaty," reads a statement posted on the website of the Ukrainian president on Thursday evening.

The European Commission on October 28 allowed Russian gas giant Gazprom to increase its quota in the throughput capacity of the strategic Opal gas pipeline in Germany. The European Commission agreed to exempt OPAL from the third energy package until 2033, a source said. "This gives Gazprom an additional 40% out of OPAL's capacity of 25.6 billion cubic meters," the source said.

This expands Gazprom's access to 90% from 50%. The European Commission will reserve 10% of capacity, which may be increased to 20% given demand from third parties. The European Commission also retains the right to revise the arrangement if demand on the part of third parties increases.

Opal is an extension of the Nord Stream 1 pipeline on the territory of the European Union. Supplies from Russia are transmitted along it from the bed of the Baltic Sea through Germany to the Czech border.

Since Gazprom is a co-owner of the Opal pipeline, it falls within the scope of the Third Energy Package, which the EC adopted in 2009 and does not allow gas suppliers to occupy a dominant position on the market.

Earlier, Gazprom was permitted to use only half of the pipeline's capacity. The European Commission at the end of October ruled to increase Gazprom quota of using OPAL to 90%.