SHANGHAI: China's yuan strengthened through the day in holiday-thinned trading on Monday, reaching its highest level in three-and-a-half months against the US dollar at the official local close, following a much strengthened official midpoint.

The spot market opened at 6.5745 per dollar and, by the 0830 GMT domestic close, settled at 6.5404, the strongest such close since Sept. 13. If the yuan closes at the level in the night trading session, it would have gained around 0.55 percent of its value from the previous late night close of 6.5765 per dollar last Friday.

Its offshore counterpart also followed Monday's trend and was changing hands at 6.5405 per dollar.

Recent advances have pushed the yuan's year-to-date gains to around 6.2 percent against the dollar. It declined roughly 6.5 percent in 2016, the worst annual performance since 1994.