A letter from Russian President Vladimir Putin to the heads of 18 European countries on problems in gas supplies shows the importance of the issue of energy security, EU Commissioner for Enlargement and European Neighborhood Policy Stefan Fule has said.

"The EU will respond jointly to the letter, in order to agree on consultations with Russia and Ukraine with a view to ensuring security of supply and transit," Fule said at a plenary session of the European Parliament in Strasbourg on Wednesday.

He said there was interdependence between the EU and Russia in the energy field.

"The EU is the largest market for the Russian gas and oil. In reaction to recent developments, the European Commission will, as requested by the European Council, conduct an in-depth study of EU energy security and will present a comprehensive plan for the reduction of EU energy dependence," Fule said.

He added that the European Commission was committed to facilitate an agreement between the Slovak and Ukrainian gas operators on the reverse flow. He also said that the Ukrainian government was aware of the need to reform the energy sector, in line with the Energy Community commitments and displayed determination to commence these reforms.