London's Heathrow airport, Europe's busiest air hub, faced further disruption on Sunday with around one in three flights cancelled following the recent imposition of new anti-terror measures.
Three days after British police foiled an alleged plot to explode US-bound passenger jets, travellers' hopes of getting their journeys back on track were dashed, with about 30 percent of flights cancelled.
The cancellation news, which was revealed on Saturday by the British Airports Authority, has led to a row with the airlines that operate at the group's facilities.
Following the alleged plot, severe restrictions were imposed on what passengers can bring into plane cabins, with only essential items allowed such as money, travel documents and medications carried in see-through bags.
The new measures caused widespread delays in boarding aircraft and forced many airlines to cancel flights at Heathrow. The hub usually flies an average of 1,250 flights per day, serving around 190,000 customers.
At London's Gatwick and Stansted airports, between 15 and 20 percent of flights were cancelled on Sunday.
BAA has argued that the measures, which also require all passengers to have a body search, were not sustainable.
On Sunday, British Airways, which accounts for 40 percent of air traffic at Heathrow, said it cancelled 30 percent of its Heathrow operations for the day, in line with BAA's request.
However, BA Chief Executive Willie Walsh has strongly criticised BAA, arguing that the operator was "unable" to provide a robust security search process and baggage operation.
Ryanair, Europe's biggest no-frills airline, which uses smaller airports around London, has also challenged the British government to help services return to normal.
"It is vital that the government works with the UK airports and airlines to prevent the collapse of the London airports," Ryanair Chief Executive Michael O'Leary said Sunday.
Ryanair wanted the body search requirement revised down from 100 percent of passengers to the normal 25 percent, he said.
"These numbers still allow any suspect groups or routes or individuals to be body searched," O'Leary added.
"More importantly they will allow the main UK airports and the UK air transport system to return to normal which is the most important message we can send to these extremists."
British Home Secretary John Reid has hinted that the stringent security checks may only be temporary.
"We understand this causes huge inconvenience to the airline operators for instance, the airports and the travelling public," he told BBC television on Sunday.
"That is why the extraordinary regime that we have had to bring in as a result of extraordinary circumstances is time limited."
In Washington meanwhile, US Homeland Security chief Michael Chertoff said that the US government would announce new airline security rules later Sunday - but added that a complete prohibition on carry-on luggage was "unlikely".