Police said the case was registered based on a complaint from the election officer.
Congress MP H Vasanthakumar was arrested for alleged corrupt practices and staying in Nanguneri assembly constituency in the district in ''violation'' of election rules during a bypoll held there on Monday, the police said.
A case has been registered against him under Indian Penal Code sections, including 171-H (Illegal payments in connection with an election), and under section 123 of the Representation of the People Act (corrupt practices), they said.
Vasanthakumar, whose resignation on his election to Lok Sabha necessitated the bypoll in Nanguneri, was later produced before a court which released him on bail.
Earlier, after being detained, he was taken to the Nanguneri police station.
Police said the case was registered based on a complaint from the election officer.
Though the MP claimed he was on his way to his home in nearby Palayamkottai, police said he was detained at a place where the MP need not have to go for reaching his destination and there may be some hidden agenda.
Officials said as per election code leaders and workers of political parties other than those residing in the district should not stay in the constituency on the election day.
They also said a case would be registered against Tamil Nadu Congress Committee president K S Alagiri for staying in Nanguneri and conducting a press meet at Reddiyarpatti violating the code of conduct.
In a tweet, Vasanthkumar said he was detained while proceeding to his house in Palayamkottai and asked should he need permission to visit his home.
Nanguneri is seeing a direct contest between DMK backed Congress nominee ''Ruby'' R Manoharan and AIADMK''s Reddiyarpatti V Narayanan.