Severe power shortages are having an increasingly devastating impact on the lives of North Koreans, in temperatures that do not rise to freezing point even at noon, and are wreaking havoc on the fragile economy, a senior government official said.

North Korea's energy crisis was the reason behind Pyongyang's decision last October to restart a mothballed nuclear power plant, the official said in an interview this week.

That move, along with Pyongyang's withdrawal from the Nuclear Non-Proliferation Treaty and its expulsion of U.N. nuclear inspectors, put the country on a collision course with the United States - which has labelled North Korea part of an "axis of evil" along with Iraq and Iran.

Washington has said the North has already built at least one or two nuclear weapons using plutonium derived from earlier activities at its Yongbyon research reactor, which the North has said it is preparing to restart.

Pyongyang is adamant the recommissioning is purely to stem big shortfalls in its electricity supply.

"This is why we must construct and operate nuclear power plants. These nuclear power plants are meant only for power generation for the Korean people," Kim Myong Chol a senior official at the Ministry for Electricity and Coal, told Reuters.

North Korea said last week it had put the atomic facilities at Yongbyon, at the centre of its suspected weapons programme, "on a normal footing".

Nuclear experts reject Pyongyang's electricity argument because the Yongbyon plant is a small military research reactor with insignificant power generation capacity.

SERIOUS SHORTFALLS

But Kim said North Korea has been suffering serious electricity shortfalls since it closed Yongbyon in 1994 under an agreement with the United States.

The terms of that deal, signed amid concerns the plant could produce weapons-grade plutonium, called for a U.S.-led consortium to build light-water reactors for North Korea and provide 500,000 tonnes of heavy fuel oil a year to make up any power shortfall.

Light-water reactors cannot produce weapons-grade material.

But Pyongyang says Washington failed to honour the agreement by delaying the construction of the reactors and by failing to deliver on promises of fuel oil.

A Foreign Ministry official told Reuters the fuel oil deliveries had been sporadic - either not appearing at all or arriving in such quantities they overburdened storage capacity - before they were suspended entirely last December.

The suspension - prompted by a U.S. belief that North Korea was developing nuclear weapons in breach of the 1994 agreement - has compounded a power shortage that is having an impact at all levels of North Korean society.

"This is totally due to the U.S. side and a lot of people have serious grievances against the U.S. because of the power," said Kim.

"Because of this - we are failing to give our people electricity for lighting," said Kim. "You can easily imagine how uncomfortable it is without lights."

NO POWER, NO LIFTS

Hence the frosty scene at the Study Hall, an imposing 100,000 square metre (1.076 million sq ft), marble-clad building in the heart of the capital, and elsewhere in Pyongyang.

Many of the city's 2.8 million people live in high-rise apartment blocks which, without electricity, become almost unbearable to live in, said Kim.

"Without electricity we cannot pump drinking water to the high floors and when there is no power there are no lifts," he said.

Outside the city, the crisis is biting just as hard.

No power means no water can be pumped into irrigation ditches already parched by drought. The power cuts stop trains on the electrified system.