Liquids, such as hair care products, were also barred on flights in both Britain and the U.S., raising the possibility that authorities were searching for a liquid explosive.
As part of the foiled Bojinka Plot to blow up 12 Western airliners simultaneously over the Pacific Ocean in the mid-1990s, terrorist mastermind Ramzi Youssef had planned to put together an improvised bomb using liquid in a contact lens solution container.
Huge lines formed at ticket counters and behind security barriers at Heathrow and other airports in Britain. Ed Lappen, 55, a businessman from Boston, who was traveling with his wife and daughter to Russia, found himself unable to travel further.
"We're safe, we're OK," he said at Heathrow. "Now my daughter is going to get a shopping trip in London."
Hannah Pillinger, 24, seemed less concerned by the announcement. "Eight hours without an iPod, that's the most inconvenient thing," she said, waiting at the Manchester airport.
Most European carriers canceled flights to Heathrow because of the massive delays created after authorities enforced strict new regulations banning most hand baggage.
Heathrow's block on incoming traffic applied to flights of three hours or less, affecting most of the incoming traffic from Europe, an airport spokesman said on condition of anonymity in line with airport policy.
Officials at Frankfurt's airport, Europe's second-busiest, Schiphol in Amsterdam and Charles De Gaulle in Paris said Heathrow-bound planes could instead land at their airports if they needed to.
London's Heathrow airport was the departure point for a devastating terrorist attack on a Pan Am airplane on Dec. 21, 1988. The blast over Lockerbie, Scotland, killed all 259 people aboard Pan Am Flight 103 and 11 people on the ground.
The explosive was hidden in a portable radio which was hidden in checked baggage.
Associated Press Writer Lara Jakes Jordan in Washington and Matt Moore in Frankfurt, Germany, contributed to this report.