The Malaysian ringgit and Chinese yuan on Thursday hit their strongest level since last July's currency reforms, helped by speculation that the pace of their appreciation is likely to speed up in coming months.
This in turn pushed the Singapore dollar to its highest level in about 1-1/2 weeks.
The Thai baht hugged a tight range as market attention remained fixed on the country's political scene, while the rest of Asia's currencies inched lower in step with the yen
The yuan firmed to 8.0348 against the dollar, the highest level since the July 21 revaluation.
The ringgit hit 3.7030 per dollar - its highest level since a peg versus the dollar was abandoned on the same day as China's currency reform.
Dealers said expectations for higher Malaysian interest rates were boosting the ringgit. They added that renewed speculation that both China and Malaysia could tolerate stronger currencies was lifting the yuan and ringgit.
"If China allows greater flexibility, presumably Malaysia would get a little less involved in the market," said Westpac senior currency strategist Sean Callow. "Malaysia is also in the firing line from the US to let the currency strengthen."
The Singapore dollar rose as high as 1.6177 per US dollar, up almost a fifth of a percent from levels traded late in Asia on Wednesday and moving closer to more than seven-year highs struck earlier this month at about 1.6128 per dollar.
"The Sing dollar has always been seen as a proxy play for further yuan and ringgit strength," said Jimmy Koh, head of treasury research at United Overseas Bank in Singapore.
"We are running up to increased US pressure on China about the yuan. But it will be hard for the Sing dollar to strengthen significantly beyond the 1.6128 area unless the yuan strengthens sharply."
Traders said the rally in the Singapore dollar was also encouraged by upbeat sentiment towards the economy.
The baht was steady at about 39.10 per dollar, off Wednesday's 2-week low of 39.32, but still seen vulnerable to political uncertainty.
Thai Prime Minister Thaksin Shinawatra returned from the provincial campaign trail on Thursday to protesters massed outside his office and doubts that his April 2 snap election can go ahead.
The Election Commission said on Wednesday that the election called by Thaksin to counter a campaign to oust him might have to be delayed as it was unlikely to fulfil constitutional rules.
"It hasn't been confirmed that the election will be delayed but this is not good for the baht," said a trader in Bangkok.
"Yesterday the baht gained on the talk that Thaksin would resign. That would have reduced the uncertainty but now we have gone back down and the baht is still very sensitive to politics."
Elsewhere, the yen eased after Bank of Japan Governor Toshihiko Fukui said it was too early for the central bank to lift rates from near zero.