China-Russia energy cooperation -- a crucial part of the relations between the two countries -- has once again come to the fore as Chinese President Xi Jinping is to start a visit to Russia on Friday.

The following is a chronology of major events of China-Russia energy cooperation since 1996.

-- In December 1996, then Chinese Premier Li Peng visited Russia and the two sides announced the establishment of the Joint Commission for the Regular Prime Ministers' Meetings. Particular sub-committees were founded under the mechanism to facilitate collaboration in trade, technology, energy and transportation.

-- In October 1999, the two countries started the construction of Tianwan Nuclear Power Plant, the largest ever bilateral economic and technical cooperation project, which produces energy with the biggest capacity in China. The project, put into business operation in 2007, saw the start of its second-stage construction in December 2012.

-- In 2008, advocated by heads of state of the two countries, a negotiation mechanism on energy was established at the vice premier's level.

-- In July of that year, then Chinese Vice Premier Wang Qishan and his Russian counterpart Igor Sechin initiated the China-Russia energy negotiators' meeting. At the meeting, Wang urged the two countries to uphold the long-term and comprehensive cooperation and market-oriented principle to achieve mutual benefits and win-win results.

-- In August 2009, Wang and Sechin signed a China-Russia Intergovernmental Agreement on Oil Cooperation at the fourth energy negotiators' meeting in Beijing, making effective a basket of agreements on pipeline construction, crude oil trade and loan.

At their sixth energy negotiators' meeting, Wang and Sechin signed a stream of agreements and memos to facilitate trade on oil, coal and electricity.

-- The year 2011 saw more tangible fruits of China-Russia energy cooperation, as oil pipelines began operation in January, annually transporting 15 million tons of oil from Russia to China for as long as 20 years.

The two countries expanded their cooperation into the field of natural gas at the seventh energy negotiators' meeting, signing a protocol on bilateral cooperation in the sector.

-- In April 2012, an Russia-China electricity transit line with 500 kv began operation.

-- Also in 2012, the two countries held the ninth energy negotiators' meeting, during which the two sides signed four more documents to enhance bilateral energy cooperation.

Xi is due to visit Russia, Tanzania, South Africa and the Republic of Congo between March 22 and 30 on his first overseas tour after being elected head of state last week.