Neither of the two men, reportedly US residents, was on any watch lists.
Two Yemenis arrested in Amsterdam on suspicion of planning a terror attack have been released, prosecutors in the Netherlands have said.
An investigation failed to find any evidence against the two men, the Dutch national prosecutor’s office said.
They were arrested on Monday upon arriving at Amsterdam airport on a flight from the US after a request from US authorities.
US officials later said they did not believe they were planning an attack.
“Two men from Yemen in custody since Monday on suspicion of possible involvement in the planning of a terrorist act, were freed this evening,” the Dutch prosecutor’s office said in a statement.
“From investigations in the United States and in the Netherlands there has been no indication of the men’s possible involvement in any criminal act,” the statement continued.
The two men have been identified as Ahmed Mohamed Nasser al-Soofi and Hezam al-Murisi.
They had both been travelling to the Yemeni capital Sanaa, and were arrested on arrival at Amsterdam’s Schiphol airport on-board a United Airlines flight from Chicago. They were not sitting together.
They had checked luggage onto an internal flight in the US that they did not then take. Officials in the US say it appears they missed the flight and were re-routed by United Airlines to travel via Amsterdam.
That flight, from Chicago’s O’Hare to Washington Dulles International Airport, was called back once it was found they were not on board.
US officials believe the two men did not know each other and were not travelling together.
One of the men had earlier been stopped by airport officials on a connecting flight from Birmingham, Alabama.
He was found to be carrying $7,000 (£4,500) in cash and when his luggage was searched, officials found a mobile phone strapped to a medicine bottle, as well as knives and watches.
The luggage was cleared for the flight after it was not judged to be a threat but there was speculation that the chain of events could have been a dry-run for a terror attack, testing the US flight security operations.
Customs authorities said it was not uncommon for people travelling to the countries like Yemen to be carrying large amounts of cash and that valuable items are often found bundled together.
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