The courts orders come close on the heels of Sri Lankan President Maithripala Sirisena's visit to India on May 13 during which he and Prime Minister Narendra Modi discussed among other issues the problems faced by Indian fishermen.
While 13 fishermen, arrested on April 15, were set free by the Oorkavalthurai Court, the others, detained on April 21, were ordered to be released by a court in Mannar, local Fishermen's Association president Emirite said quoting information received by him.
The other group of 21 fishermen were from Pamban and Thangachimadam, he said.
However, their boats had not been released, he added.
Chief Minister Jayalalithaa had last month urged Modi to take immediate action in securing the release of all 55 fishermen and 91 fishing boats, detained by the Sri Lankan navy in recent months.