Toxic gas began leaking again from a factory owned by LG Chem in southern India's Visakhapatnam early on Friday, an official said, triggering a wider evacuation after at least 11 people were killed following a leak from the site in the wee hours of Thursday.

"The situation is tense," district fire officer N. Surendra Anand told Reuters, adding people in a 5-kilometer (3-mile) radius of the factory were being moved out.

Hours earlier, authorities had said that the situation was under control at the plant on the outskirts of Visakhapatnam, where a leak early on Thursday sickened hundreds of people.

The factory is operated by LG Polymers, a unit of South Korea's biggest petrochemical maker LG Chem Ltd.