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Offshore funds sold the ringgit and the won , two of the best-performing emerging Asian currencies in August.
However, the won hit a six-year high against the yen and South Korea's foreign exchange authorities were suspected of intervening to stem its strength there, some traders said.
The Philippine peso fell as local banks covered short positions in the dollar.
China's yuan slightly eased after the central bank set its guidance rate marginally lower.
The dollar hit its highest against the yen since January and hovered near a one-year peak to the euro.