A nationwide blackout has left the whole of Bangladesh without power, after a transmission line bringing electricity from neighboring India failed.

The blackout, caused what officials described as a "technical glitch", swept across the South Asian country at around 12pm local time (6am GMT) on Saturday. Officials insisted that power had been restored to many parts of the country within a few hours.

Masum-Al-Beruni, managing director of the state-run Power Grid Company of Bangladesh, refused to fully explain the cause of the blackout, but told the Associated Press that the energy provided had used back-up generators to restore power to some parts of the country by 3pm.

Power was expected to return to the capital, Dhaka, a city with an estimated population of 15 million, by Saturday evening, Beruni said.

"One by one, we have begun restarting all our substations that supply electricity in Dhaka. The city will get power back as soon as possible," he said.

Dhaka's hospitals and the international airport were able to continue operating using emergency generators to supply power.

Mir Motahar Hossain, an official from the Power Grid Company of Bangladesh said engineers were also working to restore the power transmission link from India. "Our work is progressing fast, we hope to restore the system to a great extent, if not entirely," he said.

Blackouts, blamed on the country's ageing grid infrastructure and inefficient management, are common in Bangladesh. Saturday's blackout was the worst since 2007, when a cyclone that killed 2,500 people caused a power outage that lasted several hours.

It is estimated that more than a third of Bangladesh's 156.6 million population do not have access to electricity.

In an attempt to tackle this, Bangladesh has signed agreements with energy companies in Japan, China, Malaysia and the US to build power plants and boost energy infrastructure, and began importing electricity from India in October 2013. Currently the country can generate 11,500 megawatt of power – less than 0.0008% of the UK's energy production.