London's ambition to overtake New York as the world's preeminent city faces a big obstacle: its gateway, Heathrow Airport, is enough to make visitors feel like flying home before they even see Big Ben, Buckingham Palace or the City financial district.

Notorious security checks, a labyrinthine layout, and shoddy service combine to form the "Heathrow Hassle". With fears mounting of chaos when the city hosts the Olympics in 2012, government officials and business figures are calling for urgent improvements at the world's third-busiest airport.

Recently, Heathrow has come under a barrage of criticism. London Mayor Ken Livingstone called it a shame on the capital. A junior government minister claims the airport is so infuriating that it could hurt London's business prospects. And a business executive remarked that some people will do anything to avoid flying through Heathrow.

The airport once was a name that evoked the jet-set allure of international travel. In recent years, it has become associated more with complaints about crowded terminals, long shuffles through security and passport lines, lost luggage and a depressing decor.

The hammering began with news that Heathrow will seek a broad injunction against protests planned at the airport for mid-August by groups opposed to plans to build a third runway, which opponents say will severely increase noise and air pollution.

Green groups said the injunction is so broad it will allow police to detain potential protesters not just at the airport but on parts of the London Underground and rail network and on highways near Heathrow.

"This is the mother of all injunctions. We've long known the airport operators to be arrogant, but trying to ban five million people from coming near them is conceited even by their standards," said John Stewart, chairman of the HACAN group that opposes the new runway.

Livingstone was livid. "Someone there must be out their skull," the outspoken mayor said on on July 31, referring to officials at the British Airports Authority, which runs Heathrow and London's other two airports, Gatwick and Stansted.

"What BAA has done is guarantee massive coverage of what was going to be a minor encampment."

Livingstone did not limit his criticism to the protest row. "Certainly Heathrow does shame London. It is typical of the English short-termism, lack of planning, lack of investment," he said. "It's quite clear the current management, and management before them, thought they could keep people almost as prisoners in this ghastly shopping mall so they can extract vast sums of money from them while they wait in appalling conditions."

A BAA spokeswoman said the airport has been plagued by the lengthy legal and planning process required for improvements. For example, its nearly completed fifth terminal was held up for 20 years by red tape. Terminal 5 is to open in March and will allow the airport to raise its annual passenger capacity by 30 million, the spokeswoman said.

Heathrow was designed to serve about 45 million passengers a year but now sees around 68 million.

BAA also plans refurbishments, new inter-terminal transport and other projects it says will make Heathrow a new airport by the 2012 summer games.

Economics secretary Kitty Ussher warned that the airport's hassles may discourage business.

Sir Thomas Harris, vice chairman of Standard Chartered Capital Markets, told The Financial Times that Heathrow faces stiff competition from rival transport hubs. "There are lots of people who will fly through Amsterdam, Paris or Frankfurt or do almost anything to avoid a Heathrow connection if they can."