"They were arrested as a result of operations carried out over the last month," police spokesman and superintendent Prishantha Jayakodi said.
There were several search operations in Jaffna leading to the arrests, Jayakodi said.
The 45 ex-members of the LTTE were arrested by the police's Terrorist Investigation Division (TID).
Sri Lankan defence establishment maintains that despite the military defeat of the LTTE in 2009, the group's remnants and sympathisers are making attempts for revival.
