The Homeland Security Department (search) announced new rules Thursday to better identify cargo shipped into and out of the country, and said that it ordered airlines to conduct more thorough daily inspections of their airplanes.

The airline security directive, issued Monday to all commercial passenger airlines that fly within the United States, followed an embarrassing incident in which box cutters remained hidden in jetliners' lavatories for five weeks. In October, Nathaniel Heatwole, a student from Damascus, Md., hid box cutters and other banned items aboard two Southwest Airlines (search) planes, where they were found by maintenance staff.

Brian Turmail, a department spokesman, said the directive includes a catalog of areas that must be checked. Previously, he said, there wasn't enough clarity about what kinds of compartments needed to be inspected.

The new cargo rules require electronic manifests identifying freight shipped by truck, rail, plane and ship to be sent to Customs and Border Protection (search) officials before the goods reach the border.

"They'll look for trends and they'll look for red flags, such as mislabeled cargo or a record of past violations that might cause a container to be labeled high risk," said Homeland Security Secretary Tom Ridge, in announcing the new rules.

Customs now gets some advance information on cargo carried by plane, rail and truck. The information, though, is provided voluntarily and isn't always complete. Cargo declarations no longer will be allowed to arrive on paper with a shipment.

Officials said the electronic information will be compared with law enforcement and commercial databases to target potentially dangerous shipments that need to be inspected.

Congress ordered the changes last year because of fears that terrorists could smuggle chemical, biological, or nuclear weapons into the country. Customs officials say they can identify high-risk cargo by reviewing shipment data against the databases and in light of strategic intelligence.

Only a tiny percentage of air, rail and truck cargo is currently inspected.

The rules are similar to those that require ocean carriers to provide detailed information on the contents of containers destined for the United States 24 hours before they are loaded onto ships at foreign ports. Ocean carrier companies will now have to provide this information electronically.

Steve Alterman, president of the Cargo Airline Association, said the rules are reasonable.

"Our business is predicated on fast, time-definite delivery, and the final version of the rules takes this fact into account while at the same time ensuring that Customs has the information necessary to target suspect shipments," Alterman said.

But Martin Rojas, spokesman for the American Trucking Associations, said the trucking industry is concerned because a plant's production schedule could be upset if shipments are delayed by as little as a half-hour.

"We're not sure what impact this will have on just-in-time delivery that's done primarily by trucks," Rojas said.

He cautioned that delays may be caused by truckers who have to wait for clearance before they can leave with their freight.

Shippers that don't comply could be fined or their cargo could be refused entry.

Customs officials said the new rules take effect Dec. 5. They include:

-- Information on freight coming long distance by cargo or passenger plane would have to be sent four hours before landing in the United States.

-- Information on cargo coming from countries close to the United States -- such as Mexico, Canada and countries in Central America and the Caribbean -- would have to be provided soon after takeoff because flight times are shorter.

-- Information on cargo arriving by rail would have to be provided two hours before arrival.

-- Information on cargo sent by truck would have to be provided at least 30 minutes before arrival.