The book, 'Economy of Conflict Regions in Sri Lanka: From Embargo to Repression' had been published by the East West centre in the United States.
Another book by Rohan Samarajiva, from LirneAsia, a Colombo-based regional policy think tank, had been detained by customs from December.
Samarajiva's book, "ICT infrastructure in emerging Asia, Policy and Regulatory roadblocks" released by the Indian unit of academic publishing house, Sage, was launched in India in December.
Sri Lanka's customs chief Sarath Jayathilake was quoted in the report as saying that the detention was not brought to his attention and he was not aware why the books were seized.
"We usually detain these books if it’s a matter of security and we refer them to Defence (Ministry) or the Government Information Department," Jayathila