BSR, a subsidiary of state oil company Petrovietnam that operates the Dung Quat Oil Refinery in the central region, said crude oil prices fell 74 percent year-on-year to $18.5 per barrel in April due to lower demand globally caused by restrictions to curb the spread of Covid-19.

Falling domestic travel demand and the ban on international flights also caused sales to drop in April and May, it said in a statement.

There were signs of improvements starting last month when it reported a post-tax profit of VND1.4 trillion ($60.4 million) as oil prices started to rise in May.

The rebound in domestic aviation, with 70 flights a day in June compared to just over 40 in the same month last year, and a resumption in economic activities is reviving fuel demand.

Vietnam’s other fuel giants, such as distributors Petrovietnam Oil and Petrolimex, reported multi-million dollar losses in the first quarter.

The oil industry expects profits to fall 59 percent this year, according to financial data provider FiinGroup.