The proposal was made at a meeting between Vietnamese Prime Minister Pham Minh Chinh and Japanese Finance Minister Shunichi Suzuki in Hanoi earlier in the day, the government said in a statement.

Japan is the largest source of official development aid to Vietnam, and is the Southeast Asian country's third largest source of foreign direct investment.

Vietnam is studying the possibility to build the 1,545 km (960 miles) railway with a possible price tag of up to $64.8 billion, according to state media.

At the meeting, Chinh also asked Japan for help to "restructure stakes" at Nghi Son Refinery and Petrochemical, Vietnam's largest oil refinery, the government said, without elaborating.

The $9-billion refinery is 35.1% owned by Japan's Idemitsu Kosan Co, 35.1% by Kuwait Petroleum, 25.1% by Vietnam's state oil firm PetroVietnam and 4.7% by Mitsui Chemicals Inc.

The 200,000-barrel-per-day refinery early last year cut its run rate following a disagreement between shareholders about financing for crude. Idemitsu Kosan said at the time it had no plan to give fresh financial aid to the refinery.

(Reporting by Khanh Vu; Editing by Aurora Ellis)