China and Russia are to deepen their existing energy industry cooperation after signing a deal to supply oil to China worth $270 billion over the next 25 years.

The deal will see the supply of 365 million metric tons of oil to China starting from next month, according to media reports.

Igor Sechin, the chief executive of Russian state-controlled oil giant Rosneft, was widely quoted after being interviewed during Russia's annual economic forum in Saint Petersburg, who said deliveries could start as early as this year.