Russia has become the largest seller of cheap crude oil to China since the international sanctions imposed on Russia as a result of the war in Ukraine.
As of May this year, Chinese crude oil imports from Russia have increased by 55% compared to last year, making Russia the largest supplier of oil to China, instead of Saudi Arabia.
China has increased its purchases of Russian oil despite declining demand as a result of sanctions and a slowdown in the economy.
In February, China and Russia announced that their friendship had "no limits".
Chinese companies, including Sinopec and Genoa Oil, have been hit hard in recent months.
According to the Chinese General Administration of Customs, 8.42 million tons of oil were exported last month.
In comparison, China bought 7.82 million tons of crude oil from Saudi Arabia. Thus, Saudi Arabia, which used to be the largest exporter of oil to China, came second.
The West is responding economically to the Russian invasion of Ukraine. In March, the United States and Britain announced they would ban Russian oil, while Europe said it was taking steps to reduce its dependence on Russian gas.
The BBC's Global Trade correspondent in Dharsheni says not only China but India has also increased its purchases of Russian oil.
Russia's revenues have not been affected by the rise in demand for Russian oil, which was feared after the invasion of Ukraine.
However he acknowledged that their numbers were not enough to defeat Trump's government.
On sanctions on Russian oil, US President Joe Biden said the move was aimed at "hitting the lifeblood of the Russian economy."
Energy exports are Russia's main source of income, but sanctions are also affecting Western consumers.
The think tank Center for Research on Energy and Clean Air said in a report last week that within 100 days of the invasion of Ukraine, crude oil exports would cost Russia about ً 100 billion.
However, its exports declined in May.
Of this, EU imports accounted for 61%, valued at about 59 59 billion.
However, Russia's gross domestic product (GDP) from oil and gas exports is declining, reaching more than بل 1 billion a day at its peak in March.
But Ukraine's costs for the first 100 days of the war far exceed Russia's revenues, with the Center for Research on Energy and Clean Air estimating 87 876 million a day.
According to Monday's figures, China also imported 260,000 tonnes of crude oil from Iran last month. This was his third shipment since December.
China has been buying Iranian oil despite US sanctions on Tehran.