Interfax cited him as saying that the existing contract was for 38 billion cubic metres per year and that the two sides were discussing the possibility of increasing that by between 5 and 10 billion cubic metres.

Miller was quoted as saying that Gazprom would cover any extra demand using its own resources.

Deliveries of gas to China via the Power of Siberia pipeline are due to begin at the end of December in 2019, but the project is only expected to reach full capacity in 2025.

(Reporting by Andrey Ostroukh and Oksana Kobzeva; Writing by Andrew Osborn; Editing by Kirsten Donovan and David Evans)