China, facing pressure over pricing of rare earths of which it is the top exporter, denied any manipulation, saying prices only reflect market conditions. World prices of rare earth elements, used in making hi-tech products, in green energy and aerospace alloys, have shot up lately and China has come under focus as it supplies 90 percent of the world market. Zhu Hongren, spokesman and chief engineer at China\'s Ministry of Industry and Information Technology, told reporters Thursday rare earths prices were low earlier but now reflect market conditions brought on by huge demand, China Daily reported. He said prices of ytterbium, one of the 17 elements known as rare earths, has surged more than 10 times since 2009 and more than three times since January 2011. The current price of ytterbium is about $90 a kilogram. He said prices earlier were far below market value because of illegal extraction, environmentally unsound expansion and smuggling. However, the State Council, China\'s powerful Cabinet, has set regulations on mining of rare earths, and a special rare earths office within his ministry supervises the sector. The ministry had earlier assured China will provide a stable supply to the international market. The report said China produced more than 120,000 tons of rare earths last year, with 87,000 tons for domestic use and 34,600 tons for exports. Output quota is expected to grow by 5 percent this year.