The Indian rupee extended falls to a fresh record low on Wednesday, while the Indonesian rupiah touched a successive four-year trough due to bond outflows, with its key 11,000 per dollar support level widely expected to be tested soon.
The rupee fell as much as 1.9 percent to 64.44 per dollar as dollar buying by large state-run banks and custodian banks intensified in the mid-afternoon.
The rupiah fell up to 0.9 percent to 10,780 to the greenback, its weakest since April 2009.
It came under pressure from higher bond yields and importers' dollar bids, although the central bank was spotted intervening to support the currency, traders said.
The Malaysian ringgit also turned weaker before the country's second quarter current account and economic growth data later in the day.
The Thai baht hit another 13-month low on selling from real money and hedge funds.
Bank of Thailand left its benchmark interest rate unchanged at 2.50 percent, as expected, saying that this level remains appropriate for helping the slowing economy regain momentum.
The dollar broadly inched higher as investors braced for a U.S. Federal Reserve report later in the day which may shed light on when it will start to trim its stimulus policy. Concerns over such tapering have prompted outflows from emerging markets back to the United States.
Financial markets in the Philippines are closed for a holiday and Taiwan's markets are also shut due to a typhoon.