China's yuan currency remains substantially undervalued and it is in Beijing's own interest to let it appreciate more rapidly to ward off inflation risks, U.S. Treasury Secretary Timothy Geithner said on Wednesday.

In a speech ahead of a state visit to Washington next week by Chinese president Hu Jintao, Geithner held out the prospect of more cooperation on China's bid for high-tech goods if Beijing was willing to let its currency rise in value more swiftly.

(Reporting by Glenn Somerville and David Lawder, editing by W Simon )