Russian President Vladimir Putin is scheduled to speak in Moscow on June 16 at the start of a gathering of energy sector leaders from around the world.
Putin is addressing some 5,000 delegates from public and private firms in 65 countries who are attending the World Petroleum Congress – a weeklong event that takes place every three years.
The World Petroleum Congress has particular importance for Moscow due to Russia's conflict with the West over the Ukraine crisis and Russia's gas dispute with Kyiv, which could impact Gazprom's deliveries to the European Union.
Rising oil prices since the seizure of territory in Iraq by the Islamic State in Iraq and the Levant has also focused attention on the event.
OPEC Secretary-General Abdullah el-Badri is listed among the delegates along with the chief executive of Britain's BP, Bob Dudley, and bosses from Russia's Gazprom and Rosneft.
Based on reporting by AFP and ITAR-TASS