Japan's Idemitsu Kosan said it would proceed with a $9 billion oil refinery project in Vietnam as it had reached a final investment decision with co-investors Mitsui Chemicals, Kuwait Petroleum International and PetroVietnam.

Idemitsu, Japan's third-largest refiner, said construction of the 200,000 barrels per day (bpd) Nghi Son refinery and chemical complex would start next month.

Most of the scheme would be paid for via project financing agreements of up to $5 billion, involving $2.3 billion in loans from the Japan Bank for International Cooperation (JBIC) and the Export-Import Bank of Korea (KEXIM) and loans totalling $2.7 billion from commercial banks, Idemitsu said

The remaining $4 billion would be directly financed by Idemitsu and its co-investors. Of this amount, Idemitsu would invest $1.4 billion, the company said in a statement.

Idemitsu had said in January a final investment decision on the project, with commercial operations of the complex planned in the second quarter of 2017, was expected by June.