DHAKA: More than 100 people fell ill in Bangladesh after inhaling gas that leaked from a fertilizer factory in the port town of Chittagong, officials said on Tuesday.

Police and the fire brigade worked to contain the spread of ammonia that began on Monday night and authorities were able to plug a leaking pipe after several hours, said Mesbah Uddin, the district's deputy commissioner.

"The leakage has been repaired but a few hours more will be needed to get the situation back to normal," Uddin said.

Safety standards in Bangladesh have come under an international spotlight in recent years after a series of fires in garment factories, and the collapse of a garment factory complex, in which many hundreds of workers have been killed.

Uddin said about 50 people remained in hospital on Tuesday afternoon. The rest had been sent home after treatment.

The state-owned factory producing diammonium phosphate (DAP) fertilizer is on the bank of the Karnaphuli river, across the water from Chittagong, but wind pushed the gas from a leaking pipe toward the city.

Residents of the area were told to stay indoors.