People trying to join militant groups in Iraq and Syria have been travelling on cruise ships in order to avoid airport surveillance to reach the conflicted areas in the Middle East including Turkey, said the international police body Interpol.
According to the BBC, Interpol said that checks to passenger lists should be extended to cruise operators from airlines before the issue becomes more grievous.
Interpol's outgoing chief, Ronald Noble said that all countries should conduct checks more and more on cruise lines.
There are no figures on how many militants have taken this route to travel to war zones in the Middle East as yet.
However, a recent United Nations report said that there were around 15,000 foreign jihadists from more than 80 countries fighting with Islamic State (IS) and other extremist groups in Syria and Iraq.