Hyundai Engineering & Construction signed a $5 billion (6.4 trillion won) deal with Saudi Arabia's state oil company Aramco to build a mega complex for petrochemical production in the Middle Eastern country, the land ministry said Sunday.The deal, which will advance the Amiral project packages No. 1 and 4, is the largest contract won by a Korean builder with Saudi Arabia. Aramco is the owner of Amiral Petrochemical Plant.