The march, scheduled for August 16 - two weeks before the first anniversary of the Princess's death - is backed by both the Anglican and Catholic churches.

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It is expected to attract thousands of people.

Issue of 'safety'

The Royal Parks Agency said the organisers had been given permission to assemble in Hyde Park, which is "a traditional place of assembly.

"But they can not disperse in Kensington Gardens because logistically it is not possible."

The Agency said the small size of the park and the likely numbers expected to attend the march meant that there was a risk to public heath and safety.

But march organisers say they should be allowed to end the march in Kensington Gardens as it was the focus of public grief following the Princess's death.