Vinacomin, Vietnam's largest coal miner, said it had significantly boosted sales to fuel domestic power plants at the same time as the country is ramping up its coal imports to try to avoid a repeat of last year's power shortages.

The Southeast Asian country, a regional manufacturing hub heavily reliant on coal for power generation, has over the recent years faced pressure to maintain sufficient power supplies during heatwaves.

Coal-fired power plants account for 37.5% of Vietnam’s total installed power generation capacity, but in recent weeks has been responsible for around 67% of total electricity output, according to data from state utility Electricity of Vietnam.

The company's coal sales to power plants totalled 15.3-million metric tons in the January-April period, up 13.8% from a year earlier, the state-run miner, formally known as Vietnam National Coal Mineral Industries Holding, said in a statement this week.

Vinacomin said its monthly sales to power plants in May are expected to be a record 4.1-million tons, without giving comparative figures.

The country, which hosts large manufacturing operations of multinational companies like Samsung Electronics, Foxconn, Intel and Canon, in March vowed there would not be electricity shortages this year.

However, it has struggled to increase domestic coal production and has had to ramp up imports to feed coal-fired power plants. Coal imports in the first four months of this year rose 68% from a year earlier to 20-million tons, according to government data.

Vietnam's total coal output in the first four months of this year fell 1.2% from a year earlier to 15.3-million tons, the data showed.