MOSCOW, May 23 (RIA Novosti) - Russia should not be alarmed over the European Union's aim of diversifying its energy supplies, a presidential aide said Tuesday.

Tensions have risen in recent months in Europe - which gets 25% of its gas supplies from Russia - over the intentions of state-owned energy giant Gazprom regarding European markets, and about increasing dependency for energy supplies on the country. An EU-Russia summit is scheduled for Thursday at the Russian Black Sea resort of Sochi.

But Sergei Yastrzhembsky, President Vladimir Putin's pointman on relations with the EU, said: "The European Union considers diversification of energy resources and their supply sources as one of the ways to enhance its energy security. We [Russia] are not against this."

He said Russia had never had a monopoly on the supplies of energy resources, and that the EU's aspirations were legitimate.

"Russia is the No.1 supplier of natural gas to the EU, but it meets only one third of Europe's demands, and we are second in oil supplies ... Consequently, Russia is not a monopoly supplier," he said.

But Russia, as a seller, can also diversify its outlets, Yastrzhembsky said, adding that "this should also be considered."

Energy will be one issue on the agenda of the Russia-EU summit at Sochi. Other issues include the long-running impasse around Iran's controversial nuclear program, as well as agreements on visa facilitation and readmission. Yastrzhembsky said the sides had also reached general agreement on the document to replace the Agreement on Partnership and Cooperation, which could expire next year if either side renounces it.

"There is already a large field of agreement on this question, and Russia and the European Union both say that a new agreement should be comprehensive, broad, and legally binding - in other words, it should be ratified by both sides," he said, adding that suggestions had been made that the new agreement should last for 10-20 years, or even not have a time limit imposed on it.

Yastrzhembsky also said Moscow was not content with the European Energy Charter, which was signed in the Hague in 1991 and sets down principles for international energy including trade, transit and investment.

"We believe [the charter] has placed Russia in unequal conditions, which is why it is necessary to sign an additional protocol to the charter to remove Russia's concerns," he said.