SOCHI, Russia - Russian President Vladimir Putin on Monday formally launched the start of natural gas supplies to China via the Power of Siberia pipeline, a move he said would help trade between the two countries reach $200 billion by 2024.

The pipeline was launched at a televised ceremony watched by Putin and China's President Xi Jinping via video link.

(Reporting by Vladimir Soldatkin in Sochi and by Ekaterina Golubkova and Maria Kiselyova in Moscow; writing by Tom Balmforth; editing by Andrew Osborn) ((Tom.Balmforth@thomsonreuters.com;))