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SEOUL, Feb 24 (Reuters) - The South Korean won rose to a four-month closing high on Friday, marking its fourth straight gaining session as the dollar weakened broadly after U.S. Treasury Secretary Steven Mnuchin's comments cast doubts on the Trump administration's promised tax reform policy.
The won extended gains on South Korea's finance minister's remarks about current dollar-won volatility earlier in the session, but stepped back after currency authorities said they are watching foreign exchange rates closely.
The won was quoted at 1,131.5 to the dollar at the conclusion of onshore trade, highest since Oct. 20. It was up 0.5 percent compared with Thursday's close of 1,137.3.
The local currency touched as high as 1,127.6, up 1.7 percent during past four days of gains. For the week, the won gained 1.3 percent, its largest weekly percentage gain in six weeks, and up 6.7 percent on a yearly basis.
Meanwhile, South Korean shares slipped on stock-selling from foreign investors and domestic institutions.
The Korea Composite Stock Price Index (KOSPI) closed down 0.6 percent at 2,094.12.
Offshore investors offloaded a net 122.6 billion won ($108.4 million) worth of KOSPI shares for the day, snapping their six-day buying spree. (Reporting by Dahee Kim; Editing by Gopakumar Warrier)