Most Asian currencies fell against a firmer dollar on Friday, with the Indonesian rupiah and the South Korean won declining the most, as intensifying panic over the coronavirus outbreak sent investors scurrying into the world's reserve currency.

The dollar's appeal was also boosted by the Federal Reserve's move to inject $1.5 trillion in short-term liquidity and change the durations of Treasuries it buys to mitigate the coronavirus-induced economic stress. "The overriding theme from the last 24 hours is that markets are hunting for US dollars, and don't really care what rates they pay to get them," Jeffrey Halley, market analyst at OANDA, wrote in a note.

Reflecting the demand for the greenback, the benchmark US Treasury yields fell, he said. In Asia, the Indonesian rupiah and the Korean won were the top losers as investors trimmed exposure to risky assets. The rupiah, being one of the high-yielding emerging currencies, sees ample foreign investment, but risk aversion sparked by the coronavirus pandemic has caused the recent unwind, said Sim Moh Siong, a FX strategist at Bank of Singapore.

Indonesia has been among the most proactive countries to roll out measures to shield its economy and currency, with the central bank purchasing bonds for two consecutive days and the finance minister introducing a second stimulus package worth $8 billion. The rupiah slid 2% to its lowest since November 2018, while the won, whose movement is closely linked to its stock market, hit a four-year trough.

The trade-sensitive won benefited when the United States and China signed an interim trade pact earlier this year before worries of a global recession weighed on investor sentiment and led to heavy equity capital outflows, Siong said. Indonesian and South Korean stocks also plunged, triggering circuit breakers.

The Thai baht, the Taiwan dollar and the Malaysian ringgit weakened between 0.1% and 0.8%. Among gainers were currencies of oil-importing India and the Philippines, benefiting from an overnight drop in crude prices. Meanwhile, all Asian currencies were on track to post loss for the week during which oil prices crashed and global central banks and governments unveiled measures to contain the impact of the coronavirus.