The European Union must tighten airport security to stop terrorist attacks, the European Commission said after an official review exposed shortcomings.

The bloc boosted security checks at some 700 airports after the September 11, 2001, hijacked airliner attacks on US cities but the EU executive said controls could be improved further.

It highlighted concerns about freight security, access to cockpits and guidelines on dealing with unruly passengers.

"The 40 or so inspections carried out by the European Commission since February 2004 to check for proper application have identified a number of shortcomings and needs and the Commission is therefore today proposing this revision," the Commission a statement.

The current rules set out specifications for passenger security controls and the use of detectors to check for hidden weapons and explosives.

In an evaluation of the rules, the Commission said the EU's 25 member states had to make it easier to use new security technology as it emerged on the market, as well as make changes based on the lessons learned from fighting terrorism.

It also said parts of the rules needed to be clarified and simplified and that there should be common security requirements for air freight. Cargo carriers currently operate under different national standards.

"With what we are proposing today ... distortions for market operators will be taken away," Commission transport spokesman Stefaan de Rynck told a regular news briefing.

"This harmonised security approach will actually be to the benefit of the aviation industry."

Mr De Rynck said the Commission was concerned about in-flight security, including access to cockpits and how to deal with unruly passengers. But the EU executive would not be forcing member states to put armed air marshals on planes. The Commission's inspections included random checks at 29 airports and assessments of national authorities' quality control plans, Mr de Rynck said.

"(We) try to get through metal detectors with prohibited items and see what happens, he said, adding the Commission also checked access to restricted areas and security checks for airport staff and aircraft crews.

Any shortfalls had been reported confidentially to the EU states concerned. When asked if the Commission would name problem airports, Mr de Rynck declined, saying: "We are not a helpdesk for terrorist groups, to explain to terrorist groups what they can do in certain airports to pass certain inspection systems."

He added: "We send confidential reports based on ... inspections to the member states and expect them to take immediate action."