China's yuan weakened against the dollar on Friday amid fresh speculation that the Chinese currency will depreciate after the conclusion of the G20 summit in the city of Hangzhou. "People believed that the central bank would keep the yuan stable ahead of the G20 meeting as it usually does in cases of major political and diplomatic events," said a trader at a European bank in Shanghai. "Now speculation has flared up that the central bank may allow the yuan to depreciate after the summit." The G20 Summit hosted by China ended on Monday with world leaders saying that monetary policy alone could not lead to balanced growth, and pledging not to devalue their currencies for competitive gain. The People's Bank of China (PBOC) set the midpoint rate at 6.6684 per dollar prior to market open, weaker than the previous fix of 6.662. The spot market opened at 6.6729 per dollar and was changing hands at 6.6758 at midday, 108 pips weaker than the previous close. If the yuan closes at the midday level, it would be 0.1 percent stronger for the week. Globally, the dollar slipped from its overnight highs in Asian morning trade on Friday, on track for weekly losses in a week marked by continuing uncertainty about U.S. monetary policy. Traders said the dollar's performance was not a reason for the yuan's weakness on Friday, as recent data has offered a glimpse of how weak sentiment was hitting the Chinese currency. China's foreign exchange reserves fell to the lowest since 2011 in August, data showed on Wednesday, dropping $15.89 billion in their biggest monthly decline since May. The fall came even as China achieved a foreign trade surplus of $52.05 billion for the month, official data issued on Thursday showed. "The figures came as no surprise to us as corporates have actively purchased dollars this year amid lingering worries over yuan depreciation," said a trader at a Chinese commercial bank in Shanghai. "As corporates keep more dollars on hand, official foreign exchange reserves are likely to continue to drop for the rest of this year." The yuan has depreciated 2.7 percent versus the dollar so far this year under pressure from the prospect of another U.S. interest rate hike and amid a slowdown in the world's second-largest economy. As the yuan showed fresh signs of weakness, speculation also revived concerning the PBOC's intervention in the swaps markets to help control expectations of yuan depreciation, traders said. Four traders reported that some state banks conducted one-year swap trading deals overnight, with two traders suspecting these were carried out on behalf of the central bank. The other two traders believed the state banks extended their swap deals conducted a year ago to hedge risk.