The head of Saudi Arabia\'s state-run oil firm advised South Korean builders on Wednesday to hire more Korean supervisors for their construction sites in Middle Eastern countries in order to increase profits. In an interview with Yonhap Infomax, a financial news arm of Yonhap News Agency, Khalid A. Al-Falih, CEO of Saudi Aramco, said, \"(South Korean) companies are losing a lot of money by relying on not qualified supervisors that are brought from other nations.\"  \"My advice to Korean firms is to bring more Korean supervisors,\" he added. Al-Falih said the foreign supervisors working at Middle Eastern plant construction sites of South Korean builders are less competent than their Korean counterparts. A lack of supervisory control at construction sites was a major reason behind the massive operating losses incurred by local builders in the first quarter of the year. a Aramco, through placing huge orders for industrial plants worth trillions of won every year, has a great impact on the business of global builders working in the Middle East. \"I think our relationship with Korean EPC company is extremely good,\" he said, adding \"They are really exemplary partners to us.\" EPC stands for engineering, procurement and construction. Meanwhile, he said Saudi Aramco will steadily invest in the refinery facilities of S-Oil Corp., South Korea\'s third-largest refiner. The Saudi Arabian oil company is the largest holder of S-Oil with a 35 percent stake. Saudi Armaco, the world\'s biggest oil company, established a subsidiary named Aramco Asia Korea Ltd. in South Korea last year in a bid to tap into the local renewable energy market. Saudi Armaco has 260 billion barrels of oil reserves, accounting for 25 percent of global oil reserves. The volume of gas reserves held by the company ranks fourth worldwide.