AP Photo/Kevin Wolf

Liquids and gels are now banned from U.S. flights for fear that they may hide the materials for engineering explosives.

The next terrorist attacks on civilian aircraft could be carried out by passengers who hide their bomb ingredients in innocent-looking containers for talcum powder, baby formula or medicine bottles and assemble their weapon behind a locked restroom door, security experts warn.

The announcement Thursday of a foiled terror plot aiming to blow up flights from London to the United States using explosives hidden in hand luggage pointed to a potential new chapter in the battle against airline terrorism: a world of hours-long security checks, visual inspections of prescription drugs, and bans on bringing liquids or laptops on board.

Several bomb-disposal experts and troubleshooters for airline security interviewed by The Associated Press said mobile phones, computers, wrist watches or anything else with a battery should be prohibited from flights.

Perhaps most chillingly, they warn that security staff at airports are not looking for the right things anymore - and the change in tactics required is likely to overwhelm current security standards.

"That theater we see, of people taking off shoes, is not going to stop a suicide bomber. The terrorists have already sniffed out the weak spots and are adopting new tactics," said Irish security analyst Tom Clonan, who noted that security measures usually adapt to the last attack, not the next threat.

He said that a terrorist group will almost certainly try to blow up a plane with a bomb assembled on board unless security measures improved fundamentally.

Anti-terrorist authorities in Britain and the United States declined to describe the bomb design used by terrorists in the foiled plot - whether they were primarily liquid or, more likely, contained liquids in a more complex ingredient list.