(QHA) -

Russia's state-controlled energy giant Gazprom has signed a long-awaited memorandum of understanding on a huge natural-gas deal with China, RFE/RL reports.

The accord, announced today, came on the sidelines of a visit to Shanghai by Russian President Vladimir Putin.

There were no pricing details on the deal, however, which is believed to involve Russia supplying 38 billion cubic meters of gas per year to China for the next 30 years via a new eastern pipeline linking the countries.

It has been unofficially valued at more than $400 billion.

Gazprom CEO Aleksei Miller is quoted as saying that the China contract price is a commercial secret.

Russia and China have been working on a deal for more than a decade, but a final agreement had been delayed due to price disagreements.