The AIADMK has attacked the ruling DMK over the "heinous act".
Six people were arrested for allegedly assaulting, stripping and urinating on two Scheduled Caste men from the district, police said on Thursday. The men were also robbed.
Several political parties denounced the crime and called for concrete measures to prevent such incidents in the future.
The six people have been identified as M Ponmani, S Nallamuthu, R Ayiram, B Ramar, M Siva and Lakshmanan, all in the 21-25 age group, police said.
The six men were said to be under the influence of alcohol when they accosted the Dalit men and asked them to reveal their caste, police said. When they did so, the six men assaulted and stripped them, and then urinated on them.
The two youths were returning after a bath in the Thamirabarani river when they were assaulted, the Thachanallur police said.
The police have registered cases against the six accused under various sections of the Indian Penal Code and also under the Scheduled Castes and the Scheduled Tribes (Prevention of Atrocities) Act.
According to the victims, who are currently undergoing treatment at the Tirunelveli Medical College hospital here, the gang also robbed them of two mobile phones and silver jewellery, and extorted Rs 5,000 from them.
"They appeared to be high on ganja (cannabis). They called us towards them and asked about our caste and native place when we were getting ready to get on our motorcycle after a bath in the river on Monday. No sooner had we answered than they began attacking us with sticks and knives," the victims said.
One of the victims had to contact his office to have Rs 5,000 digitally transferred to the gang. Once the money was credited, the six men took the motorcycle owned by one of the victims to withdraw money from a nearby ATM.
"However, two of them fled upon seeing the police on patrol and we took advantage of the situation and escaped," the victims told reporters.
Condemning the "heinous act", AIADMK General Secretary Edappadi K Palaniswami said the incident proves that caste-based atrocities have become rampant after the DMK came to power in the state.
"This is a shameful act. Instead of making it a case of robbery, the police should take stringent action on those involved. The government should provide appropriate compensation to the affected SC youth," Mr Palaniswami said in a post on social media platform X.
Strongly condemning the attack, CPI state secretary R Mutharasan said such human rights violations are unacceptable in a civilised society.
"It's regrettable that such incidents are on the rise in Tirunelveli district. Concrete steps should be taken with political determination and social concern to prevent such incidents from happening in the future," he said in a release, and sought a probe and appropriate punishment for the culprits.
Pattali Makkal Katchi founder S Ramadoss called for strict action against the culprits. TNCC legislature party leader K Selvaperunthagai also condemned the incident.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)