NEW DELHI, May 22 (Xinhua) -- At least nine people were killed and more than 20 others injured after police opened fire to control a group of unruly protesters in the southern Indian state of Tamil Nadu on Tuesday, local media reported.

Though authorities have not yet confirmed the number of deaths in Tamil Nadu's port city of Tuticorin, local Minister D. Jayakumar told the media that the state government was considering compensation for those "shot dead" and the injured.

According to the minister, police resorted to firing after over 20,000 people, who were staging a protest demanding the closure of a copper smelting plant in Tuticorin, suddenly went on a rampage, vandalizing government property and offices.

"The police firing was unavoidable," he said.

The protests have been going on in the city for the past three months, but intensified in the last couple of days, following reports that the company owning the copper smelting plant was seeking renewal of its licence for another 25 years.

The state's main opposition DMK party slammed the government for failing to address the concerns of the local people. "The plant should be shut down," opposition leader M.K. Stalin told the media.

Some five years ago, hundreds of people were hospitalized after they complained of breathlessness and nausea following a gas leak from the plant.