The long-serving president of Russia's state-owned railway company, Vladimir Yakunin, confirmed late Monday that he would step down next month when he is expected to become a senator.

Yakunin, 67, is close to President Vladimir Putin and is on the United States sanctions list over the Ukraine crisis. He has headed Russian Railways, or RZhD, since 2005.

Known for his Orthodox Christian beliefs, he is set to become a senator in the upper house of parliament representing Russia's westernmost region of Kaliningrad.

The upper house is seen largely as a rubber-stamp body for laws backed by the Kremlin, with any dissension rare.

"I plan to leave the company after the elections are finished," Yakunin told RIA Novosti state news agency. Russia holds local and regional elections on September 13, including in the Kaliningrad region.

His imminent resignation was expected after the acting governor of Kaliningrad, who is standing in September, on Monday included Yakunin in his list of candidates for senators.

The Vedomosti business newspaper wrote Tuesday that Yakunin is considered "one of the functionaries closest to Putin."

Yakunin was one of the co-founders of the so-called Ozero Dacha, an association of luxury real estate owners bringing together an influential group of individuals around Putin.

Such a shakeup within Putin's inner circle would not happen without his consent, political analyst and former Kremlin advisor Gleb Pavlovsky told Vedomosti.

Under Yakunin, Russian Railways has privatised some of its functions and introduced high-speed trains on flagship routes but has struggled to expand lucrative freight traffic.

This year it received subsidies of 30 billion rubles ($458 million at the current exchange rate) while last year it made a loss of 99.3 billion rubles.

Russia's sprawling railway network fully connects the country from Kaliningrad in the west to Vladivostok in the far east. For passengers, trains are punctual if often shabby.

The Kommersant business daily said Tuesday that Yakunin's job change was the first move to the senate by a figure close to Putin since former Leningrad region governor Valentina Matviyenko became a senator in 2011.

An engineer by education, Yakunin served as a diplomat to the United Nations in the late Soviet era. Under Putin, he served as deputy transport and railways minister. He became first deputy president of Russian Railways in 2003.