By Ruma Paul
DHAKA, Oct 5 (Reuters) - Bangladeshi officials were investigating on Wednesday why power was cut to about three quarters of the country, halting the vital garment sector and telecommunications services for about 10 hours.
Electricity was fully restored just before midnight on Tuesday, government officials said.
"We suspect a transmission line experienced a technical glitch that led to a cascade of failures throughout the national power grid," Mohammad Hossain, the top official at the government's power cell division, told Reuters.
The grid malfunctioned at around 2 p.m. (0800 GMT) on Tuesday, leading to blackouts across up to 80% of the country.
Telecoms services and work in the lucrative export-oriented garment industry, which supplies to clients such as Gap Inc , H&M and Zara, ground to a halt.
Grid failures generally happen when there is a big mismatch between demand and supply, sometimes due to unexpected or sudden changes in power use patterns.
Power division secretary Habibur Rahman said officials were investigating the possibility that the failure originated in a substation near Ghorashal, 40 km (25 miles) from the capital, Dhaka.
"Our investigation team is in Ghorashal now. Once we get the report from them, we'll know what caused it," Rahman said.
Bangladesh generates three quarters of its electricity from imported natural gas and has been facing frequent power cuts this year as authorities ration gas supplies amid high global prices driven up by Russia's invasion of Ukraine. (Writing by Sudarshan Varadhan; Editing by Robert Birsel)