London taxi drivers have brought Westminster to a standstill in a protest over their ban from dedicated Olympic traffic lanes.

More than 200 black cabs arrived in Parliament Square blaring their horns to tourists' bemusement.

Their demonstration is targeted at Games' organisers who developed the so-called Zil lanes available only to Olympics officials, athletes and other approved vehicles.

Jonathan Myers, of the United Cabbies group union, said: "There will be no access to these lanes for any traffic apart from the Olympics family.

"Taxis are excluded, which is unacceptable and wrong. This is a working city and we need to get around and do our job."

Parliament Square quickly ground to a halt as the drivers descended on central London for what they plan to be a two-hour protest.

Traffic soon snarled up Whitehall, Millbank and over Westminster Bridge as car horns and traffic fumes filled the air.

Mr Myers said: "We've come to Parliament so MPs can wake up and hear what we're talking about."

He believed it would "absolutely impossible" for cabbies to carry on ferrying commuters around the capital during the Games when the full lane restrictions take effect on July 25.

Motorists who stray into Games lanes face £130 fines.

The Press Association, photo by cabbie50