Asian currencies, led by the Japanese yen, were broadly firm against the dollar on Monday after soft US economic growth numbers reinforced a view that US interest rates would stay steady for a while.
But wariness about central bank intervention to curb strength in local currencies tempered some of the gains. Dealers said they suspected the Monetary Authority of Singapore (MAS) had stepped into the market to buy US dollars and sell Singapore dollars.
The Bank of Thailand said its had again intervened on the baht - which rose to a 7-year high - although the currency had started to stabilise after inflows slowed.
"The move in some Asian currencies has been aggressive in the past week, and generally there is no resistance to the direction of the move but the magnitude," said DBS Bank currency strategist Philip Wee. "Generally the big picture is still not changed - everyone is still looking for a weaker dollar."
The Thai baht climbed to 36.66 to the US dollar, its strongest level since July 1999, before pulling back slightly by late trade. A Bangkok trader said there was strong support for the dollar around 36.35, but the outlook still suggested further baht gains.
"Sellers of dollars are still strong," he said. "They (the central bank) may just come in to calm the market down." The Singapore dollar was quoted at 1.5610/20 per dollar, up about a quarter of a percent, but pulling away from a nine-year peak hit in offshore trade on Friday at about 1.5580.
A dealer said he suspected the MAS had intervened on Monday in the 1.5605 to 1.5620 per dollar area. The US economy grew at an annualised rate of 1.6 percent in the third quarter, its weakest pace in more than three years, due to a slump in the housing market, data showed on Friday.
This set a backdrop for fresh gains in Asian currencies, which hit multi-week highs last week on foreign investment inflows, gains in the Chinese yuan and weakness in the US dollar.
The yen strengthened more than 1 percent from levels traded late on Friday to about 117.20 yen per dollar, while the South Korean won firmed to a one-month high at about 942.60 to the dollar. The Taiwan dollar rose about a quarter of a percent to 33.19 per US dollar, its highest in just over a week.
The Malaysian ringgit strengthened to about 3.6380 per dollar, its highest in more than three months, while the Philippine peso gained about a fifth of a percent to 49.73 to the US dollar, its highest level in more than four years.
"Dollar/yen weighed on dollar/peso at the open, but we are also seeing demand for pesos and some corporate are coming into the market," said a trader in Manila. "The central bank could come in at the 49.70 area."