Passengers coming to Britain for the Olympics could face lengthy queues this summer because the UK Border Agency has "insufficient funding" to open all the passport control stations, a leaked letter has revealed.
Culture Select Committee chairman John Whittingdale wrote a letter to Culture, Media and Sport secretary Jeremy Hunt outlining his concerns, reports the Metro.
Mr Whittingdale said that two members from his committee had attended a briefing by Heathrow operator BAA, and said the MPs "did not leave the briefing confident that Heathrow was ready to cope with the arrival of a huge number of competitors, Olympic family and visiting tourists in timely fashion".
According to the BBC, the letter went on: "We understand that significant preparations have been made to accommodate unusual sporting equipment, special lanes for the Olympic family, welcoming arrangements for competitors and additional Olympic ambassadors.
"However, far less thought seems to have been given to the issue of how to deal with long queues at immigration.
"The UKBA (UK Border Agency) representative suggested that there was insufficient funding to ensure all passport stations would be open."
He continued that this could have an impact on tourism, adding: "While visiting tourists will understand that the Olympics is a busy time, if the wait (at immigration) is in excess of an hour it may deter tourists from returning.
"The second impact may be that planes cannot unload their passengers into the terminal due to capacity being exceeded. This would lead to circling in the air, planes being left on runways or planes blocking gates."
Shadow Olympics minister Tessa Jowell echoed his sentiments, saying: "Tourism could be adversely affected for years to come if people have to wait for an unacceptably long time to get through border control.
"Failure to act will put at risk all the economic benefits that the Olympics has the potential to bring."
In response, Border Force has said they are working with BAA to ensure they are ready to deal with extra passengers, adding: "There isn't a trade-off between strong border security and a good passenger experience - Border Force should be delivering both."
Guess which venues these London Olympics 2012 events will be held at:
London Olympics 2012: Guess the venue
Heathrow 'not prepared' for Olympics, warn MPs
The Prime Minister will have a prime view of the Beach Volleyball competition, which will take place in a specially created temporary arena, complete with sand. But where is it?
Beach Volleyball will take place at Horse Guards Parade, the usual home of the Trooping of the Colour which happens every year on the Queen's official birthday. Wonder if she'll be watching the Volleyball?
The London 2012 Triathlon will take place here, as will the Marathon Swimming. It's a park within easy reach of the West End, and it has been open to the public since 1637, but any ideas which park it is?
The Marathon Swimming and Triathlon events will take place at Hyde Park, the largest of the Royal London parks.
Around 20,000 broadcasters, photographers and journalists are expected to be working from here, at the 24-hour media hub from which the Games will be shared with an estimated four billion people worldwide. But where will they all fit?
The International Broadcast Centre is situated in the north-west of the Olympic Park, which is located to the east of the city, adjacent to the Stratford City development. After the Games, the park will be known as Queen Elizabeth Olympic Park, to commemorate the Queen's Diamond Jubilee.
Opened in 2011, the venue for the canoe slalem can be found in Hertfordshire, and is the only London 2012 venue which the public can use before the Olympic Games begin. What's it called?
Lee Valley White Water Centre, on the edge of the 1,000 acre River Lee Country Park, will host the Canoe Slalom competition. Two new canoe slalom course have been built, and a 10,000 square metre lake feeds a system of pumps that provide the 300 metre course with 15 cubic metres of water per second.
Originally built for the Millennium celebrations, this well-known London landmark will host Artistic Gymnastics, Basketball, Trampoline and, during the Paralympic Games, Wheelchair Basketball. It sits on the point of the Greenwich peninsula, right on the Meridian Line. But what is it?
The O2 Arena, also known as the North Greenwich Arena or the Millennium Dome, will host a number of events during the London 2012 Olympics, including Wheelchair Basketball during the Paralympics.
This distinctive building will be the venue for Shooting, Paralympic Shooting, and Paralympic Archery during the London 2012 Games. It's located on the edge of Woolwich Common in south east London, close to the World Heritage Site of Greenwich Park. But where is it?
The Royal Artillery Barracks will host the Shooting, Paralympic Shooting and Paralympic Archery events. Four temporary indoor ranges will be built for Pistol and Rifle Shooting, with outdoor shotgun ranges for Trap and Skeet events.
This well-known exhibition centre - one of Europe's largest - will host a total of 143 sessions in five arenas across a wide range of sports, including boxing, fencing and judo. But what's it called?
The ExCel Exhibition Centre in London's Docklands.
This will be the venue for Swimming, Paralympic Swimming, Diving, Synchronised Swimming and the swimming element of the Modern Pentathlon. The building can be found in the south-east corner of the Olympic Park, but what's it called?
The Aquatics Centre will play host to 192 different events, and boasts a 50m competition pool, a 25m warm-up pool and a 'dry' warm-up area for divers. The Water Polo competition will be held next to it in the temporary Water Polo Arena. After the Games, the Aquatics Centre will be transformed into a facility for both the local community and elite swimmers.
This building, in the North of the Olympic Park, will host Track Cycling and Paralympic track Cycling. It's the most sustainable venue in the Olympic Park in terms of design and construction. But what's its name?
After the Games, a new mountain bike course and road-cycle circuit will be added to create a VeloPark for the local community, sports clubs and elite athletes. There will also be a cafe, bike hire and cycle workshop facilities on site.
This venue will have a capacity of 80,000 during the Games, and will host the Athletics and Paralympic Athletics events, as well as the Opening and Closing ceremonies. But what is it?
The Olympic stadium. It is located in the south of the Olympic Park, and is the most sustainable stadium ever built.