Police spokesman Hussein bin Hamid said the suspects were from South Africa, Egypt and South Korea, and one held both Swedish and US nationality. The Swedish Foreign Ministry confirmed that a dual national Swedish-American citizen was arrested while travelling on a US passport. The US Embassy in Libya declined comment.

Spreading Christianity is a crime in the predominantly Muslim North African country.

The four were arrested in the eastern city of Benghazi on Tuesday and are under investigation for printing and distributing books that proselytise Christianity. Police said they found 45,000 books in their possession and that another 25,000 have already been distributed.