Just three months after the biggest developing economies solddollars to support their currencies, policy makers from Colombia toChina are moving to weaken exchange rates and revive exports as theInternational Monetary Fund forecasts the slowest trade growth inthree years.

Colombian Finance Minister Juan Carlos Echeverry urged thecentral bank on Aug. 3 to boost minimum dollar purchases from $20million a day, saying the country needs “more ammunition” to drivedown the peso in the global “currency war.” The Philippines bannedforeign funds from deposit accounts and unexpectedly cut interestrates in July as the peso hit a four- year high. In China,authorities lowered the yuan reference rate to the weakest sinceNovember, which according to Citigroup Inc. will create “headwinds”for other Asian currencies.

After spending more than $59 billion in foreign reserves in Mayand June to stem currency depreciation, developing nations arereversing policies as the European debt crisis outweighs the riskof faster inflation. South Korea and Chile may weaken exchangerates to make their exports cheaper, according to UBS AG. The IMFestimates global trade will expand at the slowest pace since2009.