Russian President Vladimir Putin is due to arrive in Croatian capital, Zagreb, on June 24 to attend a summit on energy cooperation in southeastern Europe. The summit begins June 23.
High on the agenda for Putin will be a project to link up Russia's Druzhba and Croatia's Adria oil pipelines.
Croatian President Stipe Mesic called the summit, which will bring together Putin and 10 heads of state from the Balkan region (Albania, Bosnia-Herzegovina, Bulgaria, Croatia, Greece, Macedonia, Montenegro, Romania, Slovenia, and Serbia).
"Croatia, like any other country that wants to make progress in its development, must secure a diversity of energy supplies," Mesic said in comments to journalists on June 21. "That is one of the issues we want to talk about. There will be discussion about the Druzhba-Adria [pipeline project], as well."
The conference comes as the Balkans' importance as an energy transit hub is on the rise.
"The importance of the Balkan region is really increasing because the really big stake for both the Europeans and the Russians is how to transport, how to convey, the Caspian region's energy resources into Europe," said Federico Bordonaro, a Rome-based energy analyst.
Russia's oil-pipeline monopoly Transneft originally proposed the Druzhba-Adria project in 2002. But the plan, which would have extended the Druzhba pipeline to Croatia's deepwater port at Omishalj, was opposed by environmental groups.
Zeljko Tomsic, Croatia's deputy economics minister, told RFE/RL that a new proposal would instead have the pipeline transport the oil to the Italian port of Trieste.
"What we are talking about is an option in which the Druzba-Adria integrates with the Pan-European pipeline which goes to Trieste, so that the Russian oil, instead of going to Omishalj, goes to Trieste and further to Bavaria," Tomsic said.
Analysts say Putin's agenda in the Balkans is wider than the Druzhba-Adria oil pipeline project.
The European Union hopes to use the Balkans as a transit route for natural gas from Azerbaijan and Turkmenistan to Western Europe. The proposed Nabucco pipeline would transport gas from the Caspian region to Europe via Turkey and the Balkans.
Putin, however, wants to prevent this from happening, since it would give the continent an alternative to Russian natural gas and therefore reduce Moscow's political and economic clout.
"What [Russia] wants is to prevent Europe from creating alternative routes, because this would translate into a relative loss of power by Russia," Bordonaro said. "If they are able to intervene where the Europeans are trying to build their own alternative routes, then they are able to be the quasi-monopolist."
The Kremlin has made several moves recently to frustrate the European strategy.
In May, Putin, Turkmen President Gurbanguly Berdymukhammedov, and Kazakh President Nursultan Nazarbaev agreed to build a pipeline along the Caspian Sea coast. The pipeline would transport natural gas from Turkmenistan to Europe via Kazakhstan and Russia.
Russia's Gazprom has also been seeking to establish joint ventures to build large natural-gas storage facilities in Serbia, Hungary, and Romania.
"Because Europe wanted to build an alternative route, also across the Balkan regions, that would transit these resources from Kazakhstan, Turkmenistan, and Azerbaijan toward Western Europe, Russia is now stepping in, in order to manage all possible alternative routes," Bordonaro said.
(RFE/RL's South Slavic and Albanian Languages Service contributed to this report.)