A shortage of materials, rising prices and the weakness of the dollar have combined to hit shipbuilders' profits and raise fears of a rise in newbuilding prices.
Daewoo reported last month its net income in January was 40% down on the previous year, mainly because of the high cost of steel.
The Korean Ministry of Commerce, Industry and Energy announced the restrictions on Wednesday and the leading steelmakers - Posco, INI Steel and Dongkuk Steel Mill - have toed the government's line.
China
