China-Russia energy cooperation -- the crown jewel of the neighboring giants' exchanges -- has gained steam in recent years as the two countries seek to optimize common interests despite some disagreements.

During Chinese President Xi Jinping's visit to Russia, the first stop of his maiden foreign tour since taking office, the two countries agreed to build a solid strategic relationship on energy by cooperating actively in the fields of oil, natural gas, coal, electricity and new energy, according to a joint statement.

The clutch of energy agreements signed during Xi's stay include increasing electricity and natural gas exports from Russia to China, joining efforts in oil-gas exploitation and refineries construction.

On Friday, Russia's biggest oil producer, Rosneft, agreed to gradually increase oil supplies to China between 45 million tonnes and 50 million tonnes per year, three times the current level.

This will make China the biggest importer of Russian crude oil, according to media reports.

Also on Friday, Russia's natural gas giant Gazprom and China National Petroleum Corporation signed a memorandum that will see Russia delivers 38 billion cubic meters of natural gas to China per year starting 2018.

The timetable marked a significant breakthrough, as the two countries have been in talks over gas supplies for more than a decade, which has failed to produce concrete results due to pricing disagreements.

The latest development showed the two countries, though still in discrepancy regarding some areas, have adopted a more practical approach as certain disagreements cannot block the promising cooperation outlook.

For China, the world's second largest economy and the biggest energy consumer, Russia could offer oil and gas it needs to power growth, while for Russia, China would become an ideal export destination for its energy as demand in its major market -- Europe -- wobbles amid economic woes.

"In face of the profoundly complex international situation and the still grave global economic environment, China and Russia should work together more closely to enhance their comprehensive strategic cooperation," Xi said during his stay in Russia.

While cooperation at higher levels is gathering pace in the energy sector, there is a perception in Russia that China's growing economic clout will put Russia in a vulnerable position in energy trade and threaten local resources.

When asked about the "China threat theory" at the Moscow State Institute of International Relations, Xi dismissed such concerns as groundless and unnecessary.

China's take-off has brought concrete benefits to the world. In contrary, it is a weak China that the world should be concerned of, he added. Endi