VIENTIANE — Isolated, under-developed Laos brands itself the “Battery of South-east Asia”, powering its neighbours with dozens of hydroelectric plants, but frequent power outages leave its own people in the dark.

Exports of electricity to neighbouring countries including Thailand and Vietnam are a key source of revenue for the landlocked nation, designated as a least developed country by the United Nations.

But most of the power generated leaves the country and, combined with an ageing grid, that results in frequent outages and sometimes having to import electricity to meet demand.

When the power cuts out after dark in Vientiane, families wander outside to avoid the stifling heat indoors, using cell phones to light their way.

At one of the two main public hospitals, a doctor in the paediatrics emergency department is used to watching medical equipment suddenly shut down until the generators kick in.

“Over the past three to six months, we’ve often faced electricity problems, especially at the children’s centre,” said the doctor, who spoke on condition of anonymity.

“A ventilator came to a halt, but we do have a generator at the hospital.”

When old wiring recently caused an electrical fire in the alley outside the hospital, a blackout cut power to X-ray, ultrasound and ventilator equipment, she said.

Elsewhere in the city, a front-desk staffer at a health clinic said power outages occurred two to three times a week, usually announced beforehand.

Without a generator, “we have to reconnect the electricity from a store next to us”, said the staffer, who also requested anonymity in a one-party communist state where authorities do not tolerate dissent.

When the power is restored, the cry rings out across the city: “It’s back!”