The company planned to submit its study of Nhon Hoi refinery next month, Le Huu Loc, Binh Dinh's mayor, was quoted as saying in online newspaper VnExpress on Thursday.

Once the study is filed, PTT will work with the provincial authorities along with relevant central agencies before its final draft is sent to the Prime Minister for approval, Loc said.

If approved, the investor will draft and complete a technical design for the project next year and is set to begin construction three years later, according to the official.

PTT initially planned to invest $28.7 billion in the oil refinery which will be one of the world’s largest with the capacity of 660,000 barrels per day. But, the company recently pared the estimated cost to $21.5 billion, Thoi bao Kinh te Sai Gon (Saigon Times) newspaper reported in April.

The investor has asked the Vietnamese government to grant its plant similar preferences that Dung Quat and Nghi Son refineries, both invested by the state-owned PetroVietnam, enjoy, but the Ministry of Finance dismissed the proposal as “unjustifiable.”

The mega project has faced opposition from PetroVietnam, which insists that the Nhon Hoi plant will upset the supply-demand situation in Vietnam. The Vietnamese group hoped to meet 70 percent of the domestic demand for oil products with its two refineries.

However, Nhon Hoi has received support from the government as well as analysts who expect it to have a have positive impact on the economy by boosting exports and strengthening competition in the domestic market, leading to lowered gasoline prices.