The southeast Asian country joins developing nations such as China and India in establishing an oil buffer that will enhance their energy security as imports have jumped while domestic production is on the decline.

The 90-day net import level is a standard set by the International Energy Agency for its OECD members.

Vietnamese refineries will be required to maintain crude stockpiles equivalent to 15 days of their processing capacity and 10 days of oil products output, a government statement said on Friday. These would be equivalent to 30-35 days of Vietnam's net imports, it said.

The government said it planned to keep commercial oil stockpiles stable at 35 days of net imports while crude and oil products reserves at import terminals and those held by trading companies are expected to reach 20 days of the country's net imports by 2025.

The statement did not provide details on where the oil reserve storage facilities are located.

Vietnam has imported 280,492 tonnes of crude oil in the first half of this year, up 1.6 percent from a year earlier, according to government data.

The country's two refineries are estimated to meet about two-third of Vietnam's demand when its second refinery starts operations later this year.