Some of the biggest energy firms operating in Argentina include Repsol’s YPF and Pan American Energy, partowned by China’s CNOOC and Argentina’s Bulgheroni family. In the mining sector, foreign heavyweights include Xstrata PLC and Canada’s Barrick Gold Corp.

Until now, energy companies were obligated to repatriate 30% of their export revenue in dollars, while miners faced no such requirement.

Mining sector sources said the measure will increase company costs because they will be forced to trade their dollars into pesos in Argentina and then repurchase the greenbacks to make payments abroad. This will also be taxed.

Many companies have their export income committed for use to pay debts abroad, meaning they could run into problems if limits on dollar purchases in Argentina disrupt these flows.

“The measure affects [company] rights, it affects the sector’s stability. We’re analyzing whether there is room for improvement in the actual implementation, but it’s too early to say,” a mining company executive said on condition of anonymity.

Nomura investment bank said the measure, decreed in the government’s official gazette, was “bad news.”

“The message that the authorities are sending at this critical juncture is not auspicious. Faced with strong portfolio dollarization, we think they seem to be communicating that more controls are coming,” the bank said in a research note, adding the measure should boost dollar flows into the spot market by a maximum of Us$800-million per month.