The Chinese yuan firmed slightly on Thursday, as corporate demand for dollars was offset by ample liquidity from state banks ahead of the seven-day National Day holiday.

Moreover, the yuan will formally join the International Monetary Fund's reserve basket known as Special Drawing Rights on Saturday.

The People's Bank of China set the yuan midpoint rate at 6.6700 per dollar prior to market open on Thursday. That was weaker than the previous fix of 6.6681.

The spot yuan market opened at 6.6724 per dollar and was changing hands at 6.6699 at midday, 51 pips firmer than the previous session. The yuan closed at 6.663, slightly stronger than the mid-point.