Authorities said the suspects, all from Birmingham, England, were arrested Thursday night after returning on a flight from Oman, The Daily Telegraph reported.
West Midlands Counter Terrorism Unit officers arrested the men -- ages 33-39 -- as part of a "preplanned and intelligence-led" operation that police said was not "in response to any immediate threat to public safety," The New York Times reported. The men were not identified.
The men, police said, were held on suspicion of "possessing articles and documents with intent to use them for terrorist purposes overseas."
The men were being held under a section of the British Terrorism Act that makes it a crime to possess materials that create a "reasonable suspicion" they are "for a purpose connected with the commission, preparation or instigation of an act of terrorism."
A police spokeswoman would not provide details about the articles and documents the men were accused of possessing. She said British officers had gone to Oman last week to meet with authorities there but would not elaborate.