British writer Alan Shadrake was arrested as part of a criminal defamation investigation, Singapore police said.
Shadrake was in Singapore to promote his new book which examines the city-state's death penalty policy and features an interview with a former executioner.
Singapore Police Force said Shadrake was arrested yesterday.
The attorney-general's office said it will also seek contempt of court charges against Shadrake because statements in the book allegedly impugn the impartiality, integrity and independence of the judiciary.
Reports said a major book store in Singapore was ordered by authorities to stop selling Shadrake's book.
Police said today they arrested 75-year-old Shadrake after a complaint by the government's Media Development Authority.