In April, crude imports from Russia rose by 52.4 percent against April 2015, to 1.17 million barrels a day.
Meanwhile, oil shipments from Saudi Arabia dropped 21.8 percent, to one million barrels a day.
"The record high import volumes from Russia were likely fueled by independent refiners, who are storing oil that they had earlier purchased at lower flat prices," a trader with a Chinese company told Reuters.
Another source said that the demand for Russia crude is expected to drop in June because refiners would decrease purchases due to the higher oil prices.
Independent refiners have long been an important client for the Russian-produced ESPO crude due to low transportation costs and small cargo size, according to Reuters.
RBC Capital Markets commodity strategist Michael Tran told BI that Russia had become the "biggest rival to the Saudis in the single-largest oil demand growth country in the world."
"Is there a sense of urgency from the Saudis? You bet," he wrote.
Earlier, many experts noted that the key factor behind Russia’s success in the Chinese crude market was its readiness for yuan-denominated payments for oil. Riyadh is not ready to accept the Chinese currency and uses only US dollars.
Moscow and Beijing established a powerful energy alliance which changed the global oil market. In addition to increasing trade operations with oil and gas, the two countries are set to challenge dominance of the US dollar in setting prices for crude, according to Mexican economist Ariel Noyola Rodriguez.
"This creates basis for a new financial order backed by petro-yuan. The Chinese currency would soon turn into the main currency for trade operations in the Asian-Pacific Region," he wrote in an article for the foreign affairs analysis website Voltaire Network.
Last week, the Russian daily newspaper Kommersant reported that Chinese companies are considering taking part in trading futures with the Russian Urals crude benchmark.
In November 2015, Russia announced a plan to create its own oil benchmark, in a bid to establish a fair pricing mechanism for Russian oil grades.
