The man identified as Kumar from Karumathampatti had come along with son Rithish Kumar(7) to the SP office to air his grievance and suddenly poured kerosene on himself and his son, police said.
However, he was overpowered by police, they said.
Preliminary inquiry revealed that he had loaned Rs 10 lakh to Mohanraj, a jeweller, who failed to return it, despite several reminders.
Police have advised Kumar to negotiate with Mohanraj and settle the matter.
On October 23, a couple had set themselves and their two kids on fire at the Tirunelveli collectorate complex over alleged harassment by a money-lender and police.