Asian foreign exchange authorities, including central banks of Singapore, Thailand, Taiwan and Indonesia, were spotted buying dollars to stem strength in their currencies, dealers said.
Emerging Asian currencies may see more corrections as investors still hold dollar-short positions and a pullback in the euro may cause further short-covering, analysts said.
Market players will be focussing on how much further the ECB might raise interest rates after a widely expected tightening later in the day.
"If they do hike, it's difficult to envisage a statement or press conference from Trichet that gets the market more excited about the ECB outlook than it already is," said Jonathan Cavenagh, currency strategist at Westpac in Singapore.
If the euro in turn comes under pressure, he said, "that could see some Asian currencies come under modest selling pressure."
Some bet a weaker euro may cause investors to buy emerging Asian currencies against it. That would provide another boost for the Asian currencies, though a US bank strategist in Singapore said investors have already take euro-short positions against them.
Still, the corrections are unlikely to hurt the bullish trend in Asian currencies that has been fuelled by inflows to the region's stock markets amid a healthier economic outlook and as Asian central banks are seen still tightening, dealers and analysts said.
Reflecting the views, the recent laggards such as the Taiwan dollar, the Philippine peso and the Thai baht rose on Thursday.
As of Wednesday, the baht had risen merely 0.4 percent against the dollar since March 17, a day before the yen-selling intervention by the Group of Seven rich countries, which prompted investors to return to riskier assets.
In the same period, the Taiwan dollar gained 1.5 percent and the peso rose 1.8 percent, underperforming a 4.5 percent jump in the won and a 2.3 percent gain in the Indian rupee.
RUPIAH
The rupiah posted its biggest percentage fall in three months as investors covered dollar-short positions with the central bank spotted buying dollars to check its strength.
The Indonesian currency also suffered from flows linked to unwinding in local bonds, dealers said.
It lost 0.27 percent to 8,675 per dollar, the largest daily percentage loss since a 0.33 percent fall on Jan. 7, according to Reuters' calculations.
On Wednesday, the dollar/rupiah 14-day relative strength index fell to 13.135, the lowest since April 20, 2009, indicating the dollar has been oversold against the Indonesian currency.
The rupiah has benefited from expectations that the central bank may allow it to appreciate further to stem inflation.
But the central bank has intervened to slow down its strength at the same time, with its dollar purchases spotted at 8,650 per dollar.
WON
The won edged down on temporary dollar demand linked to local companies' dividend payments to foreign shareholders and to heightened caution over possible intervention by the foreign exchange authorities.
Some suspected the authorities of buying dollars while many said the purchases appeared to relate to dividends rather than intervention.
On Wednesday, the authorities were spotted more frequently than usual to check the speed of the won's strength, dealers said.
Still, the won's rising trend remain intact on continuing inflows into Seoul's stock market and with room to strengthen to 1,078 per dollar, around its high of Sept. 8, 2008.
With the expectations, exporters chased it for settlements on dips, dealers.
"Given yesterday's intervention, I see strong support (of dollar/won) around mid-1,080. But offers are pretty strong around 1,090 as everybody sees the level as high enough," said a local bank dealer in Seoul.
Foreign investors turned into net buyers of Seoul stocks in the afternoon, extending their buying streak to a 17th consecutive session.
TAIWAN DOLLAR
The Taiwan dollar hit a fresh near two-month high against the US dollar on demand linked to stock inflows and for arbitrage.
The Taiwan currency gained as much as 0.73 percent to T28.94 per the greenback, the strongest since Feb. 11.
The Taiwan dollar is facing with a resistance of T28.84, the lower downtrend channel line. If it breaks the line clearly, it has room to strengthen more, probably to T28.70, around its previous lows.
But the central bank's intervention may check the pair's gains with a US bank dealer in Singapore spotting its US dollar purchases.
BAHT
The baht broke through 30.11 per dollar, the 61.8 percent Fibonacci retracement level of its November-January weakening trend, although the central bank was spotted buying dollars
The Thai currency strengthened to as firm as 30.03 and has room to appreciate more, probably to 29.85, the 76.4 pct retracement. But it may find psychological resistance around 30.
The central bank was estimated to have bought about $100 million in the morning after purchasing close to $300 million on Wednesday although local markets were closed for a holiday, IFR Markets reported.