Hanoi: Japan’s Idemitsu Kosan has struck oil at its fourth oil-well at plot 05-1b and 05-1c offshore southern Vietnam.

The company said the oilfield was first identified through testing carried out in May and August.

Two Japanese companies - Idemitsu and JX Nippon – each own 35% of shares in the oil plots while another company – Inpex Corp – holds the remaining 30% interest.