"They are in our custody and they have not been released yet," navy spokesman Kosala Warnakulasuriya told Reuters.

"They are being held in Trincomalee," he said, referring to the island nation's eastern port city. "They will appear in court tomorrow and they are still on the boat."

Sri Lanka's navy arrested the fishermen on Sunday night for fishing in Sri Lankan waters. They were aboard two trawlers off the country's east coast town of Batticaloa, Xinhua said.