The launch ceremony of the TurkStream natural gas pipeline will be held on Wednesday in Istanbul.
The leaders of Turkey, Russia, Serbia and Bulgaria will attend the ceremony of TurkStream, according to a statement released by Turkey's Directorate of Communication.
Turkish President Recep Tayyip Erdoğan is expected to hold meetings with the heads of the states and governments to discuss bilateral relations, Libya, Syria and the regional developments.
Russian President Vladimir Putin arrived in Istanbul at 9 p.m. local time (1800GMT) on Tuesday, following his visit to Syria.
The TurkStream natural gas pipeline was built to transport Russian natural gas to Europe via Turkey.
The Nord Stream project, operational since 2011 with an annual capacity of 55 billion cubic meters, carries Russian gas directly to Germany via the Baltic Sea.
The Nord Stream 2, spearheaded by Russia's state-owned energy company Gazprom, is nearly complete and has the same annual capacity, running almost parallel to the first pipeline route.
Together they will meet the annual gas demands of a quarter of the European continent.
The TurkStream natural gas pipeline has a total capacity of 31.5 billion cubic meters, out of which the first line will carry 15.75 billion cubic meters of Russian gas to Turkish consumers.
The second line will carry 15.75 billion cubic meters of gas to Europe via Turkey.
BOTAS built the first line that will connect to Turkey's existing gas grid, while the second line, to be operated by a Gazprom-BOTAS joint venture, will stretch to the Turkish-European border in Turkey's Thrace region.
