Jun 02th, 2011, from The Wall Street Journal. HANOI—The State Bank of Vietnam has asked all state-owned firms to sell their foreign currency to banks beginning July 1, part of a plan outlined in February to eliminate the use of foreign money in the domestic market. The central bank announced the directive Wednesday in a statement on its website. It didn’t provide details on the amount of foreign currency state-owned firms are believed to hold. The central bank also asked banks to raise their reserve ratio for foreign-currency deposits maturin…