SINGAPORE -- Most Asian currencies firmed on Wednesday in tandem with stock markets, but investors' sentiment was overshadowed by talk of a shift in China's policy to let the yuan depreciate to spur the slowing economy.

The South Korean won gained 1.6 percent to 1,441.9 per dollar at one point, but it later retreated 1,465 to as foreigners kept selling local stocks and data showed the country's foreign exchange reserves fell to a near-four-year low.

South Korea's foreign exchange reserves dropped by $11.7 billion in November to $200.5 billion -- the lowest since the end of Jan. 2005, data showed Wednesday.

The Thai baht rose 0.8 percent to 35.35 per dollar as anti-government protesters ended their siege of Bangkok's airports after Prime Minister Somchai Wongsawat was forced to step down -- a respite in the country's political crisis.

"The end of PAD protest boosted the baht and triggered players to unwind dollar/baht long positions," said a Bangkok-based trader, referring to the anti-government People's Alliance for Democracy.

The MSCI index of Asia-Pacific stocks outside Japan was up 0.5 percent as of 0621 GMT, following rally in Wall Street on Tuesday.

The Singapore dollar inched up to 1.527 per US dollar but it failed to rise further amid speculation that Chinese authorities might have shifted policy to let their currency depreciate to help stimulate the slowing economy.

"The Singapore dollar generally tracks the euro and the yuan, and more so on the yuan this week after the yuan depreciation story," said a trader in Singapore.

The yuan opened at 6.8845 per dollar, hitting the lower limit of its daily trading band for the third straight session, but it was kept within the 0.5 percent range.

Analysts say a sustained yuan depreciation seems unlikely, given China's still solid trade surplus and fears that such a move may trigger a round of competitive devaluations in Asia.

JPMorgan strategists Claudio Piron and Yen Ping Ho believe that the scope for the yuan to fall on trade-weighted basis is limited even as the yuan may fall further against the dollar.

"It would appear that China is signaling its intent to appear more independent, though it is more likely responding to internal pressures by export sectors for a weaker currency," they said in a note.

"However, the chances of China engineering a longer-term trade-weighted depreciation are limited as its trading partners have far more flexible exchange rate regimes that would outpace China in a strategy of beggar-thy-neighbor depreciation."