The two girls, aged 14 and 11 years respectively, phoned Xavier, an official of an NGO 'Childline' and told him that their father was sexually harassing them daily.
When Police Inspector Shanthi, who was informed, inquired, the girls cried for help, police said.
The man, a widower, was arrested and remanded in judicial custody, police said.
He has a seven-year-old son also.