HONG KONG - Yuan forwards headed for the biggest gain this year amid mounting calls for China to allow its currency to resume appreciation before leaders from the Group of 20 nations meet on June 26-27 in Toronto.

The US Congress may push China to revalue the yuan if the nation doesn't move on its own after the G20 summit, US House of Representatives Ways and Means Committee Chairman Sander Levin said on June 16. China's one-year swap rate rose to the highest level since October 2008 on speculation the central bank will push up borrowing costs in money markets higher to cool the economy.

"Obviously there's pressure building up on China to be more flexible on the yuan," said Gerrard Katz, head of foreign-exchange trading at Standard Chartered Plc in Hong Kong. "Now that the dollar's under pressure again and equities are up, there's going to be more hot money inflows into China."