Updated

Travelers may encounter longer lines at airports as screeners focus extra attention on CD players, cameras, laptops and other electronic gadgets that terrorists might try to use to conceal weapons or bombs.

The Homeland Security Department on Tuesday sent an advisory to law enforcement personnel nationwide alerting them to the possibility Al Qaeda could use electronics to carry out attacks.

"Al Qaeda operatives have shown a special interest in converting a camera flash attachment into a stun gun type of weapon or improvised explosive device," the advisory said.

David Stempler, president of the Air Travelers Association (search), said longer lines will be a small price to pay for extra security.

"There's one thing worse than being slightly inconvenienced — it's being permanently inconvenienced," he said.

Ian Redhead, spokesman for the airport trade group Airports Council International (search), said the more intense scrutiny of electronics may at first lead to longer lines. But, he said, airports wouldn't put up with waits that last more than 10 minutes, the standard the government has set for its screeners.

"We're not going to use this as a potential excuse," Redhead said.

The advisory was the latest effort to tighten security since the government publicly warned on July 28 that terrorists may try more suicide hijackings of airplanes.

The departments of State and Homeland Security suspended two programs that allowed foreigners to stay in U.S. airports without visas while awaiting flights to other countries. The State Department also revised an existing caution for American travelers to reflect the perceived hijacking threat.

The advisory issued Tuesday said "depending on location, placement and configuration of the device, the amount of explosives that could be contained within even the smallest camera could cause collateral damage."

Among the items that will prompt increased scrutiny at airports are remote keyless door or lock openers, automatic camera flash attachments, cellular phones and multi-band or dual-speaker radios.

The advisory also said terrorists could design such devices to be used against government buildings, public areas with controlled access and security screening checkpoints.

Security directors at airports were ordered to meet with all federal screeners within the next day and review procedures for checking electronic gadgets, said Brian Turmail, spokesman for the Transportation Security Administration (search).

The TSA also is asking passengers to remove all their electronics from their pockets or bags and put them through the X-ray machine at the security checkpoint, Turmail said. Air travelers will still be required to remove laptop computers from their cases before they're screened, he said.

Michael Cherkasky, a former New York state prosecutor who was involved in the first World Trade Center bombing case, said the recent warning was no surprise since terrorists have for years tried — and sometimes succeeded — to blow up planes by hiding bombs in electronics.

"It's in the Al Qaeda manual," he said. "It's not a shock."

A thumbnail-sized circuit board inside a radio detonated the bomb that blew up Pan Am Flight 103 over Lockerbie, Scotland, in 1988.

Ramzi Yousef, mastermind of the 1993 bombing of the World Trade Center in New York City, plotted to simultaneously blow up 11 airliners by smuggling parts of bombs onto each airplane and assembling them in the lavatories, Cherkasky said.

"If they do it well, it's extraordinarily difficult to detect," Cherkasky said. Closer scrutiny of electronics is just one way that a many-layered system of airport security can detect a sophisticated plot, he said.

Airlines have struggled to regain passengers since the Sept. 11 attacks. Darryl Jenkins, head of George Washington University's Aviation Institute, said the terror warnings will keep people from flying during what should be the peak summer travel season.

"None of this is good," Jenkins said. "These are not the kinds of things that cause people to book trips."

Diana Cronan, spokeswoman for the Air Transport Association, the trade group for major airlines, said, "We are trying to work together with Homeland Security."