Central banks of Indonesia, Malaysia, Philippines and Thailand were spotted buying dollars to slow down speedy gains in their currencies, dealers said.
Even without intervention, investors have remained cautious over further gains in Asian currencies as they keep an eye on Japan's nuclear crisis and turmoil in Middle East, in addition to persistent worries about inflation in the region, analysts said.
"Given that the nuclear scare is still unfolding and unrest in MENA appears to be escalating, the risk sentiment is too weak to support Asia FX," said Andy Ji, Asian currency strategist and economist at Commonwealth Bank of Australia in Singapore.
"The inflation differential is widening on faster Asian inflation in particular. These will weigh on the Asian FX in the near-term."
Reports of progress in stabilising an earthquake-hit nuclear plant in Japan prompted investors to seek riskier assets again, but oil prices remained high, keeping inflationary pressures in the spotlight in Asia.
Although some Asian central banks were buying dollars to slow gains in their currencies, they were unlikely to push down their currencies as it would complicate efforts to fight inflation, dealers said.
"They are happy with strong currencies as they can help to control inflation, especially when other Asian currencies are strong," said a Kuala Lumpur-based dealer.
PESO
The Philippine peso broke through a falling trend line which started from Feb. 7 as local investors bet on a rate hike by the central bank later this week.
On Monday, Governor Amando Tetangco said the central bank is mainly concerned about managing inflation expectations and will support growth only as long as the inflation target would not be breached.
The peso has room to strengthen more, probably 43.298 per dollar, the 61.8 pct Fibonacci retracement of its November-January fall.
But dealers said dollar-buying intervention was spotted around 43.380 to check the local currency's gains.
Meanwhile, the country said it sold $1.5 billion of new 2026 global bonds in an offering that was "significantly" oversubscribed.
BAHT
The baht hit a near 11-week high against the dollar on demand from real money and as exporters with bearish dollar sentiment continued to support the local currency.
The Thai currency strengthened to as firm as 30.07, the strongest since Jan. 5.
The Bank of Thailand was spotted buying dollars, starting from 30.25 and lowering bid levels, but it is unlikely to reverse the trend, dealers said.
"I don't think they will lift dollar/baht... Only way they can do is just support it and not let it go down so fast," said a Bangkok-based dealer said.
WON
The won rose, but dollar demand from importers such as energy firms and state-run companies prevented it from strengthening past 1,120 per dollar.
Few currency investors expected the won to strengthen past 1,120 yet on caution over further intervention by the foreign exchange authorities to cap its gains.
Investors are also keeping an eye on Japan.
"With lower levels, I could not see offers from exporters and offshore players," said a senior foreign bank dealer in AFP
On the economic front, the country's exports during the first 21 days of the month rose 27 percent from a year ago while imports grew faster, producing a trade deficit of $2.32 billion.
Hyundai Heavy Industries said it had won a $600 million deal from BP to build offshore platforms for oil and gas production, prompting expectations for more won demand.