Update | China, Russia sign historic natural gas supply deal worth US$400b after decade of talks

China and Russia signed a long-awaited natural gas supply deal worth US$400 billion in a diplomatic boost to show the unity of the two nations.

The signing, witnessed by President Xi Jinping and his Russian counterpart Vladimir Putin, was made on the sidelines of a regional forum at which Xi warned against the establishment of military alliances in Asia and called for a new regional security co-operation mechanism.

Under the agreement, Russia's Gazprom will supply China National Petroleum Corporation with 38 billion cubic metres of gas annually for 30 years.

Gazprom CEO Aleksey Miller told Russian news network RT that the contract was worth a total of US$400 billion, but the price of gas stipulated in the deal remained a "commercial secret".

Hopes of a deal were running high when Putin kicked off his two-day Shanghai tour on Tuesday. But it could not be signed after talks between Putin and Xi that day, and representatives from the two sides continued negotiations until yesterday.

Watch: China and Russia sign huge gas deal