BEIJING, June 22 -- China's central bank set its daily reference rate for yuan trading 0.43 percent stronger, the biggest gain in five years, reflecting appreciation in the currency's exchange rate yesterday.

The daily rate was set at 6.7980 per dollar, compared with 6.8275 yesterday, and the yuan's close of 6.7976. The 12-month non-deliverable yuan forward climbed 0.5 percent to 6.6095 as of 9:39 a.m. in Hong Kong, implying traders are betting on a 2.9 percent appreciation. The yuan's exchange rate weakened 0.08 percent to 6.8030.

"The fixing was at yesterday's spot close, which indicates that true to their word, they are allowing market forces to play a greater role in determining the renminbi's value," said Mirza Baig, a Singapore-based currency strategist at Deutsche Bank AG, the world's largest foreign exchange trader. "It also indicates that ahead of the G-20, they are willing to tolerate a more rapid appreciation of the yuan."

China's central bank said over the weekend it will allow greater currency "flexibility," while maintaining the trading band, curbing inflows of short-term speculative capital and preventing "excessive" fluctuations.

Chinese authorities had prevented the currency from strengthening against the dollar since July 2008 to help exporters cope with the global financial crisis. The currency appreciated 21 percent in the three years after a managed float against a basket of currencies was introduced in 2005. Gains this time around may be more moderate because the yuan has already strengthened 16 percent against the euro this year, eroding earnings for Chinese exporters in the European Union, the nation's largest market.