AKIPRESS.COM - Stricter screening of passengers and luggage at Australian airports, introduced after police foiled an alleged "Islamic-inspired" plot for a bomb attack on a plane, will remain in place indefinitely, Reuters reported as Australia's immigration minister as saying. 

The ramped up security procedures were put in place after four men were arrested at the weekend in raids conducted across several Sydney suburbs.

The men are being held without charge under special terror-related powers. The Australian Federal Police would not confirm media reports the alleged plot may have involved a bomb or plan to release poisonous gas inside a plane.

The arrests follow last month's siege in the city of Melbourne, where police shot dead a gunman who was said to have links to the Islamic State group.

Immigration Minister Peter Dutton told reporters in Melbourne on Monday that the alleged plane bomb plot could prompt longer-term airport security changes.

Passengers at major Australian airports, including Sydney, experienced longer-than-usual queues during the busy Monday morning travel period. A Reuters witness said the queues had disappeared at Sydney Airport by lunch-time.

A source at a major Australian carrier said airlines and airports had been instructed by the government to ramp up baggage checks as a result of the threat, with some luggage searches now being conducted as passengers queued to check in their bags.