DHAKA, Bangladesh (AP) — Bangladesh was struggling to restore power hours after a transmission line bringing electricity from neighboring India failed on Saturday, causing a nationwide blackout, and officials said it would take at least 12 more hours to repair the system.

The blackout swept across the impoverished and energy-starved South Asian nation at around noon, after the transmission line experienced a "technical glitch" that led to a cascade of failures throughout the national power grid, with power plants and substations shutting down, said Masum-Al-Beruni, managing director of the state-run Power Grid Company of Bangladesh Ltd.

The company restarted some power plants and restored electricity to some areas of the country for a few hours Saturday afternoon. But the plants were not operating as normal and had to be shut down again, two power company officials said on condition of anonymity because they were not authorized to discuss the situation with media.

They said they were investigating the problem, but that it would take at least 12 hours to repair the national grid and restore power to the capital, Dhaka, a city of more than 10 million people.

Dhaka's hospitals and the international airport were continuing to operate, with emergency generators supplying power. But many offices normally open on Saturdays had to send their employees home.

"This is terrible," said Mohammad Hasan, a resident of Dhaka's upscale Bashundhara neighborhood. "We had some confidence in the government over last few years that the power sector was improving slowly. But what is this?"

As night fell Saturday, most of Dhaka remained dark, though officials said they had restored some power to strategic buildings, including major government hospitals, the president's house and the prime minister's residence.

An aide to Beruni said technicians were working to restore the link with India. "Our work is progressing fast. We hope to restore the system to a great extent, if not entirely," said Mir Motahar Hossain.

Bangladesh is considered one of the most energy-poor nations, with one of the lowest per capita electricity consumption rates in the world. More than a third of Bangladesh's 166 million people still have no access to electricity, while the country often is able to produce only some of its 11,500-megawatt generation capacity.

Power outages blamed on inefficient and dated grid infrastructure, as well as poor management, are common in Bangladesh, though Saturday's blackout was the country's worst since 2007, when a powerful cyclone that killed about 2,500 people knocked out the national grid for several hours.

Bangladesh has tried to improve its energy situation, extending access to electricity to about 3.45 million more people since 2008. Last year, it started to import electricity from India through the 400-kilovolt transmission line, which runs from Baharampur in the Indian state of West Bengal to the town of Bheramara in southwestern Bangladesh.

It also has signed agreements with energy companies in Russia, Japan, China and the United States to build power plants and improve energy infrastructure.