The explosion occurred Nov 13 in blast furnace 2 at the steel plant of Bhushan Steel Ltd., in Narendrapur village, about 150 km from Bhubaneswar.
The plant officials claimed a worker had died and about 15 were injured.
However, people in the area said that there was need for investigation, and the number of deaths may have been much higher.
The state government has launched a probe after allegations that the company concealed information about the number of those who died and were injured in the blast.
Though the local authorities sealed the blast furnace after the incident and arrested three senior company officials for negligence, protestors were demanding a judicial probe into the matter, accusing the company and the government of concealing information from them.