AN extra 600,000 people are expected to descend on London for the royal wedding tomorrow, with trade unions warning it could be a “transport lottery” in the Capital.

Drivers have been urged to avoid central London on Friday with many roads being closed for the big day.

Buses routes around Westminster, Hyde Park, Piccadilly and Trafalgar Square will be affected, but all Tube lines will be running on a normal Saturday service.

Among roads that will be closed are The Mall, The Strand, Whitehall, Victoria Street and Westminster Bridge.

Those who do venture in to the Capital by car will be exempt from the congestion charge as it’s a bank holiday.

The Overground will be suspended between Watford and Willesden Junction for engineering works.

RMT union general secretary Bob Crow warned it will be a “travel lottery” in the city, pointing to a Tube system which was “already struggling to cope.”

His comments follow three consecutive days of breakdowns on the Jubilee line last week.

London transport commissioner Peter Hendy said: “There is a real sense of excitement surrounding the royal wedding, and a great many people will be coming to central London to be a part of the various celebrations taking place. We are working with our partners to ensure that everyone can get around safely and easily, and that people not involved with the celebrations can continue to move around the city with the minimum of disruption.”