Air travellers faced stringent new security restrictions Monday following an attempt to blow up a US airliner, including a ban on going to the toilet during the final hour of some flights. Passengers in the United States and Europe found their flights during the already busy holiday season subjected to delays to allow time for increased searches and checks in the wake of the botched attack on Friday. Amsterdam-Schiphol airport was investigating how a 23-year-old Nigerian could have smuggled on board explosives that he allegedly tried to detonate as the flight from Amsterdam approached Detroit. Within the United States, passengers were told to check in four hours ahead of their departure times, while bomb-sniffing dogs were visible at airports. Airlines said passengers would now have to remain seated for the final hour of the journey, with no access to the bathroom or overhead lockers, and nothing on their laps. The news measures came in after the United States asked airlines worldwide to tighten security and airport authorities introduced extra screening and strict baggage limits that heaped hours on to check-in times. But the International Air Transport Association (IATA) called for officials to be flexible in applying the new rules. 'In the very short term, we understand the need for emergency security measures... We'd hope the authorities would adjust the procedures depending on the risks,' IATA spokesman Steve Lott said. Dino Melchior, 50, was stuck in Chicago with his parents and two children after his flight from Toronto was delayed by two hours due to heightened security. 'Apparently a new directive came out for people to be physically patted down and they weren't prepared for it,' Melchior said. 'I've never seen lines like that.' However an selfnews reporter, who travelled on the flight from New Orleans to Paris via Washington's Dulles airport, said no special security instructions were given. In London, British Airways said US-bound passengers would undergo additional screening and only be allowed one item of hand luggage. Passengers at London's Heathrow Airport accepted the procedures with good grace. 'I'm not worried at all,' said Mary Lecarpentier, who was travelling to New York to celebrate New Year. 'Sometimes there are delays and you just deal with them but we haven't experienced any.' Britain's interior minister Alan Johnson told the BBC that the government was looking at introducing full body scanners at airports. Authorities in Germany said they were stepping up security, particularly at Frankfurt, Europe's third-biggest hub. In Asia, Singapore Airlines introduced additional screening for flights to the United States from the busy Asian hub. Airline passengers travelling from Australia to the United States also faced increased searches. Since Al-Qaeda's suicide attacks with hijacked airliners on New York and Washington in September 2001 and an attempted 'shoe-bombing' on a flight a few months later, airline security has been increasing. In 2003, airlines reinforced cockpit doors and in 2006 many countries introduced strict restrictions on liquids allowed in luggage after a plot was uncovered to bomb airliners flying from Britain to North America. 