LONDON - Well-wishers gathering in London to celebrate the wedding of Prince William and Kate Middleton will be able to watch the ceremony on two giant screens in the city centre, the capital's mayor said on Thursday.

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Only 1,900 people -- from family and friends to foreign dignitaries, diplomats, soldiers and charity workers -- have invitations to watch the service inside Westminster Abbey on April 29.

Outside, tens of thousands of people are expected to line the route of the couple's wedding procession to the abbey from Buckingham Palace.    

The screens will be erected nearby in Trafalgar Square and Hyde Park, Mayor of London Boris Johnson said.

"The royal wedding will be a truly momentous occasion and we want everyone to be able to join in the celebrations," he said.

Two billion people around the world are expected to tune into television broadcasts of the royal marriage, Britain's culture minister Jeremy Hunt said on Wednesday.