CPI leader and MP Bibhu Prasad Tarai was arrested on Saturday while trying to enter the proposed steel plant site of Posco-India ahead of an anti-project rally.
"Tarai was arrested as a preventive measure to avoid any law and order problem as a large number of anti-project activists have gathered in the area," Superintendent of Police Jagatsinghpur Devdutta Singh said.
Prohibitory orders under section 144 of the CrPC has been imposed around Balitutha, entry point to the proposed plant site where anti-Posco activists have been staging a dharna, he said adding, the police personnel in strength have been deployed in the area.
About 1500 police have been mobilised as part of Orissa government's efforts to begin forest survey and land acquisition in the plant site, police said.
Terming his arrest as "undemocratic", Tarai said he was proceeding to learn about people's problem area which falls under his constituency, Jagatsinghpur.
As unrest brewed in the area following Tarai's arrest, CPI state secretary Dibakar Nayaka accused the administration and police of acting in "undemocratic and arbitrary" manner to suppress people's voicice. He said CPI would launch a vigorous state-wide agitation against it.
Seeking withdrawal of force from Balitutha, CPI-backed Posco Pratirodh Sangram Samiti (PPSS) continued its dharna since January 26 and planned a rally to he addresssed by CPI leader AB Bardhan on May 19.