Police said they were arrested at Murukkandi in Mannar district on November 26. They were presented before a local magistrate.
"It is illegal to celebrate a banned terrorist organisation," police spokesman Ajith Rohana said.
November 26 was celebrated annually by the LTTE as "Heroes' Day" to commemorate those who died in the fight to carve out a separate Tamil homeland.
The day was also the birthday of the slain LTTE leader Velupillai Prabakaran. He used the occasion to make the annual policy speech of the organisation.
MA Sumanthiran, a legislator of the country's main Tamil party TNA, said there was nothing wrong in commemorating the dead. "This is done in civilised societies so no one should try to prevent it," he told parliament.