The stakes are rising as the Thai baht faces huge selling pressure. Regional central banks made a powerful statement of intent, intervening to support the embattled currency. They will have to do far more if the onslaught intensifies. Tuesday saw co-operative currency agreements tested for the first time with the Hong Kong Monetary Authority (HKMA) buying the baht. Yesterday the Monetary Authority of Singapore (MAS) weighed in with a similar buying axe. The intervention certainly looked tough although nothing more than bluffer's intent was demonstrated thus far. Hedge funds smell weakness doubting Thailand's political commitment to a fixed exchange rate as the property and finance sectors endure extreme pain from high interest rates. The Bank of Thailand sees financial ruin in devaluation and will do everything to resist. So far the HKMA and MAS have bought the baht in small doses rather than enter much-touted repurchase arrangements. By showing their hand publicly the central banks hope speculators will flee in the face of their huge reserves. The question hedge fund managers will ask is how much taxpayers' money will the HKMA and other authorities sacrifice to defend a fixed currency system that many in Thailand believe is well past its sell-by date. Mexico remains on everyone's mind but national interest always come first.