British travellers are facing a fourth day of delays on Sunday as up to a third of flights from Heathrow Airport are set to be cancelled.

New security procedures at airports raised a row over who is responsible for the new airport security checks.

Passengers are allowed only essential hand luggage and are subject to more intense security checks after police thwarted an alleged plot to bomb a number of planes on Thursday, the Sky News reported.

British Airways' chief executive Willie Walsh accused airport operator British Airports Authority (BAA) of being unable to cope with the new arrangements.

In remarks quoted by the Sky News, he said that Heathrow's "baggage system cannot process all of the passengers bags and where passengers have been able to check their bags in, the lengthy queues in the airport security search area means that passengers are unable to get to the departure gate in time for their flight."

"We need more resources at the airport, we need more people processing passengers at check-in and through the security systems," he told the Sky News.

Ryanair's chief executive Michael O'Leary said that flights were being cancelled "solely because BAA cannot cope with the new body search requirements."

He also called on the government to provide police or army reserves to help carry out searches, though the Transport Department said that no direct request for extra security staff had been revealed.

But BAA's chief executive officer for Heathrow Tony Douglas said if extra searches were maintained there were likely to continue to be extremely long queues and more flights cancelled.