British Airways has cancelled 19 flights out of Heathrow today, but hoped a full service would resume tomorrow.

Meanwhile, it's understood that there is a backlog of about 20,000 items of lost luggage sitting in airports.

BA alone is trying to reunite about 5000 bags with their owners.

A BA spokeswoman blamed BAA - which owns Heathrow and Gatwick - for the luggage problems.

"Their (BAA) baggage system that transports checked-in luggage has had to be stopped and restarted several times. People have been checking more luggage in and are still doing so," she told the Press Association.

"There are also a number of smaller items going in and the system is not used to it. People have been checking in items such as handbags and mobile phones in carrier bags.

"It will be a few days before most of the luggage is reunited with its owners."

Meanwhile police have confirmed that looters have capitalised on the current crisis with airport thefts increasing.

There have been 52 thefts from the luggage hold at Gatwick, compared to 16 over the same period last year. While there was a dozen reported thefts at Stansted.

At Heathrow, BA has cancelled 19 shorthaul and domestic flights today. The airline expects to run a full operation at Gatwick.

There are no cancellations at Stanted or Luton today, but delays are expected.

Britain's main civil aviation union, the Transport and General Workers' Union, today demanded an urgent assessment of staffing levels in UK airport security to ensure that passenger safety can be maintained.

The union also warned that airline pressure to speed up security checks could compromise security.

"Whilst the security threat has been downgraded for now, the aviation industry has to recognise that an intensified security regime in airports will in operation," T&G National Secretary for civil aviation Brendan Gold said.

"The pressure that airlines are exerting on the airports' authorities to speed up security checks is not in the best interests of passenger security, which should not be compromised at any cost."

Furious airlines and tour operators yesterday lashed out at BAA and the government for making the situation worse for travellers than it needed to be.

The Federation of Tour Operators called for an independent inquiry into the handling of the crisis by the government and the British Airport Authority, which owns Heathrow, Gatwick and Stansted.

"It is not clear to us how airport security arrangements at times of heightened tension have improved in the five years since the 9/11 tragedy," he said.

"We call a for an independent inquiry, in the weeks to come, of the handling of this crisis by all the parties involved - especially the airports and the government's own planning for passenger security in the light of this long-recognised potential threat."

Ryanair said BAA's failure to adequately staff Stansted, combined with "nonsensical" new hand baggage restrictions, had caused delays at Stansted this morning.

"Ryanair continues to urge the UK government to defeat these extremists by returning UK air travel to normal, as they successfully did on the London Underground within 2 days of last year's 7/7 attacks," a spokesman for the Irish carrier said.

BA chief executive Willie Walsh said that the airline may sue BAA.

"Since 9/11, everyone in the industry has known there might be times when extra security measures needed to be put in place. Yet when the moment struck, BAA had no plan ready to keep Heathrow functioning properly," he said.

A BAA spokesman said the company was aware of the frustrations experienced by airlines, but would not compromise its responsibility to apply the security regime.

"Inevitably, these frustrations have been most intense at the busiest airports. Heathrow, in particular, has been singled out for criticism, and the allegation has been made that BAA lacked adequate plans to deal with the emergency," he said.

"We regret these comments, which are neither fair nor accurate. The fact is that Heathrow, the world's busiest international airport, is at the best of times significantly over-stretched because of the difficulties over many years of securing permission to grow capacity at the airport."

Click here for the BAA airport security flyer

Eased airport security measures:

  • Each passenger is permitted to carry one item of cabin baggage through the airport security search point. The dimensions of this item must not exceed: a maximum length of 45 cm, width of 35 cm and depth of 16 cm (17.7"13.7"6.2" approx) (including wheels, handles, side pockets etc.).
  • The bag must NOT contain:

- Any liquids, cosmetics or toiletries, including gels, pastes, lotions, liquid/solid mixtures, perfumes and the contents of pressurised containers - these must be checked in as hold baggage.- Cigarette lighters are NOT permitted in hold baggage or through the security search. These may be purchased airside.

  • The bag CAN include:

- Electronic equipment including mobile phones, digital cameras and MP3 players (such as iPods).- Prescription medicines in liquid form, eg diabetic kit.- Baby milk and liquid baby food (the contents of each bottle MUST be tasted by the accompanying passenger). - Laptops must be removed from the bag for x-ray.

  • All remaining items in pockets should be placed in the clear plastic bag provided, eg car keys and fobs, cash, solid food, books, newspapers, cigarettes and tobacco.
  • Pushchairs and walking aids are permitted but must be x-ray screened. All wheelchairs will be subject to search. Please note: You may be subject to a hand search by the security team and required to remove footwear to be x-ray screened.
  • Once in the departure lounge passengers may purchase any item in any store and take it onto the aircraft as normal unless you are travelling to the USA.