Nigeria, Feb. 4 -- The murder of a Saudi journalist in Turkey, the U.S. detention of a Russian asylum applicant and the abduction of a China-born Swedish citizen from Thailand all have one thing in common.

All three represent a sharp increase in countries methodically extending political repression beyond their borders with little repercussion, according to a report released by the U.S.-based Freedom House on Thursday.

Dozens of countries are using multiple tools of international law, bilateral pressures, digital media monitoring and harassment and physical threats to pursue exiled dissidents and activists, said the rights group.

Freedom House - a mostly U.S. government-funded democracy advocacy group - documents 608 cases of direct an...