Shipping line DFDS confirmed to Danish newspaper Politiken that Mansour was aboard the ferry and that the Norwegian Police Security Service (PST) had been contacted about the incident.
Neither Danish police nor their intelligence service PET would comment about the reason for Mansour's arrest. He was released on Monday.
During a search of Mansour's home police found photographic and computer equipment worth DKK 200,000 (USD 29,000), a small pistol and ammunition. Police are maintaining charges of receiving stolen property and violations of weapons law against Mansour.
Mansour has lived in Denmark for 17 years and runs the publishing company Al Nur Islamic Information. He has often been a vocal supporter of holy war and Osama bin Laden, but calls himself an otherwise "average Muslim".
