Vinod Kumar Vajpayee, president of the Noida Phase-II Industries Association, said: “There are many other companies that have seen violence over the last few years.”

Workers of Jaypee Greens in Greater Noida attacked the company’s office in 2004 and killed one person. Similarly, employees at Daewoo attacked the office of the company after it went bankrupt. Some 125 workers and 10 policemen were injured in the clashes.

“Largescale rioting like that on Monday (when Choudhary was killed and 34 others were injured) is a troubling phenomenon,” Vajpayee said.

Hindon Rubber, another company that was based in Noida, wound up operations after similar protests by employees earlier this year.

Most clashes in the past, industrialists say, have been because of expelled or suspended employees. Graziano had expelled 192 of its regular employees on July 1 and opted for contracted workers, a practice opposed by the Mazdoor Sangh leaders.

Virender Singh Sirohi, secretary of the Uttar Pradesh unit of Hind Mazdoor Sabha, said: “We had taken the issue of workers to the president and all concerned authorities; the rioting is condemnable but there are issues that need to be addressed.”

Sirohi alleges that officials at Graziano had agreed to their demands in an earlier meeting and later refused to implement the steps promised. “The frustration had been building up,” he said.

Industrialists, however, allege gangs that operate among the labourers are involved. Sahdev Sharma, chairman of the Greater Noida Industries Association, said: “We have reported about the involvement of bad elements and a few workers in the past; meetings between employees and owners have also been arranged.”

Sharma alleges the police and administration have been neglecting the situation in the area. “Assurances have been given and some action taken but this incident goes to show that all is not well.”

Sharma and members of other associations held a meeting with District Magistrate Shravan Kumar and Senior Superintendent of Police R K Chaturvedi on Wednesday to discuss security arrangements in the industrial area.

After the meeting, Sharma said: “We do not want Gautam Budh Nagar to lose its image as an industrial hub; stern steps will need to be taken in this regard.”