I consider the O'Hare failure a case of dramatic dimensions

Transport Secretary Norman Mineta

It was only at the departure gate that a random check of his hand luggage by airline staff found his other weapons - seven more knives, pepper spray and a stun gun.

Security has been increased since the 11 September attacks, but as this and other incidents demonstrate, security is still uneven at airports across the US.

And the recent lapses are pushing the US Congress to enact new security legislation.

Rush to reform

Gurung was initially arrested by police but, incredibly, was released on bail.

Subash Gurung was only caught at the departure desk

He has been re-arrested by the FBI, but they say there is no sign he was involved in terrorism.

Officials condemned the incident and renewed their call for action.

"I consider the O'Hare failure a case of dramatic dimensions. I recommend the [Federal Aviation Administration] begin enforcement actions which could lead to a substantial fine against United Airlines," said US Transport Secretary Norman Mineta.

Mr Mineta said that he would also ask the airline to retrain all of its security screeners.

Since the attacks, National Guard troops and state police have bolstered security screeners at airports.

National guard presence at airports has been increased

Bags are checked more frequently, and passengers now must present photo identification to ticket takers before they are allowed to board their flights.

Airports across the country are scrambling to install new scanning devices that are more similar to medical CAT scans than X-ray machines and will aid in the detection of explosives and plastic guns.

The US Government is also considering installing new devices including face-scanning cameras that match people's faces with those on watch lists or lists of known criminals.

Pressure on Congress

The incident at Chicago has also renewed criticism of Argenbright Security, the largest contractor of airport security screening services.

This is the worst I've seen. People are really scared. They think twice before committing to going anywhere

Travel agent Luisa Ponce

Argenbright, a unit of the UK's Securicor Plc., was last month ordered to conduct background checks on all its workers. A year ago, the company was fined $1.2m for hiring convicted criminals.

The breach of security at O'Hare Airport also added to the ongoing debate in Congress over whether security screening should be federalised.

The question of federalisation has been one of the main sticking points in Congress's effort to pass new airport security legislation.

The Senate and the House of Representatives have passed different bills, and now the houses of Congress must reconcile those differences.

President Bush wants discretion to hire private contractors or federal employees as security screeners.

He met with congressional leaders on Tuesday and urged them to come together to pass an aviation safety bill.

The speaker of the House, Representative Dennis Hastert, has said that he wants legislation passed by no later than the Thanksgiving holiday, two weeks away.

It is a one of the busiest travel times of the year in the US.

Shaken passenger confidence

President Bush has set aside $3bn extra for airport security, but the Chicago incident could damage passenger confidence all over again.

Luisa Ponce has been a travel agent for 30 years.

"This is the worst I've seen. People are really scared. They think twice before committing to going anywhere," she said.

Experts here say no security system is immune to human error, but it is the timing and the scale of the latest one which has raised anxieties again.