As China and Russia announced to strengthen cooperation in energy sector, oil and gas giants from two sides signed new deals this week.

China National Petroleum Corporation (CNPC) and Gazprom signed a long-term sales and purchase agreement for natural gas to be supplied via the Far Eastern route on Thursday, according to a press release by CNPC on Saturday.

The signing of this document is an important step towards further strengthening the mutually beneficial cooperation between Russia and China in the gas sector, Gazprom said in a press release on Friday.

As soon as the project reaches full capacity, the volume of Russian pipeline gas supplies to China will grow by 10 billion cubic meters, totaling 48 billion cubic meters per year, according to Gazprom.

"It is indicative of the exceptionally strong mutual trust and partnership between our countries and companies," said Alexey Miller, Chairman of the Russian energy giant.

Meanwhile, Russian oil producer Rosneft also signed a deal with CNPC on Friday to supply a total of 100 million tons of oil through Kazakhstan over 10 years and the crude oil will be processed at factories in northwest China to meet the country's needs for petroleum products, according to Rosneft's press release.

Last year, Russia replaced Qatar and became China's third largest gas supplier, and it is also China's No.2 crude oil supplier, according to official data.