South Korea's Pohang Steel Company (Posco) today signed a memorandum of understanding (MoU) with the Orissa government for setting up a 12 million tonne steel plant at Paradip with an investment of Rs 52,000 crore.The proposed project, when implemented, will be the largest single foreign direct investment (FDI) in the country till now, official sources said.The MoU was signed in the presence of Orissa chief minister Naveen Patnaik, South Korean ambassador to India Jung iL Choi and Posco chairman Ku-Taek Lee.Posco's executive vice-president Soung Sik Cho and Orissa's principal secretary in the steel and mines department Bhaskar Chatterjee signed the agreement.