LONDON, England (CNN) -- Airline officials have accused the British government and airport authorities of mishandling new security measures in the wake of an alleged terrorist plot.
As cancellations and delays gripped Britain's major airports for a sixth day, the head of British Airways threatened Tuesday to sue BAA, the country's largest airport operator, for financial compensation.
Analysts expect the disruptions could cost the airline more than £40 million ($75.53 million). (Full story)
"Since 9/11, everyone in the industry has known there might be times when extra security measures needed to be put in place," said BA chief executive Willie Walsh.
"Yet when the moment struck, BAA had no plan ready to keep Heathrow functioning properly," he told the Daily Mirror.
"The queues for security have wound all round the terminals like a bad dream at Disneyland."
Meanwhile, the CEO of budget airline Ryanair said the UK government had "failed to provide any leadership" following Thursday's arrest of 24 suspects in the alleged plot to blow up trans-Atlantic airliners.
Michael O'Leary told CNN that the government had failed to take quick action to help the airline industry "return to normalcy."
The government, he said, should have used military personnel to secure airports after the terrorist threat was raised to its highest level following the arrests in order to ease congestion caused by new baggage restrictions and increased passenger screening.
O'Leary criticized an initial ban on liquids of any type being permitted through the airport security, saying the London Underground subway system and the Eurotunnel have no such restrictions even though they are "as much a terrorist target as airlines."
Earlier Tuesday, Ryanair also blamed ongoing disruptions on "BAA's chronic inability to staff their Stansted security facilities, combined with nonsensical hand baggage restrictions."
The carrier said there were long security queues at Stansted and that at one point Tuesday only four out of 14 security points were open.
"The chaotic scenes at Stansted Airport show that there is no foundation to BAA CEO Stephen Nelson's claim that staffing is not a problem," a Ryanair spokesman said. (Alerts threaten discount travel)
BAA, which operates Heathrow and six other major airports, had hoped the UK government's decision to allow some hand luggage -- including mobiles phones and laptops -- back on flights Tuesday would mean an end to the travel misery. (New baggage rules)
But CNN's John Vause at London's Heathrow Airport, the worst affected, said BA had canceled 40 flights there Tuesday.
He said one in two passengers were still being called for individual searches at Heathrow.
In addition to cancellations at Heathrow on Tuesday, BA also canceled 11 flights from Gatwick. Ryanair scrapped eight services at Stansted.
Meanwhile, British investigators have searched for evidence of explosive tests in woods in High Wycombe, west of London, near where they arrested the 24 suspects. (Full story)
Security sources told CNN that the alleged plotters intended to use an electrical charge to detonate liquid explosives in planes as they flew at maximum cruising altitude over the Atlantic Ocean.
On Monday, investigators obtained a warrant to detain one of 23 suspects until Wednesday for questioning. Warrants covering the other 22 suspects were granted Friday for the same period.
Police in Britain can hold terrorist suspects for up to 28 days.
Another person arrested in the case has been released without charge, the statement said. A 24th suspect was released earlier.
Also Monday, British authorities lowered the terrorist threat alert by one level to "severe," but the security sources said it is unlikely that the level will soon drop further. ( Watch why the terror threat is eased a notch -- 2:11)
They said there is great concern about "copycats" attempting similar attacks.
The United States matched the move, dropping its alert level on flights from Britain from "severe" -- its highest rating, color-coded red -- to orange, or "high."