Culture Secretary Tessa Jowell has already earmarked a site - in Hyde Park's Lovers' Walk - for the £1 million monument to commemorate the 52 people who lost their lives in the attacks two years ago.
According to the competition brief, published by The Royal Parks earlier today, the winning scheme will have to include 'a central structure or monument of modern design incorporating and reflecting traditional aspects of important memorials'.
The scheme is being backed by the Department for Culture, Media and Sport, which has been charged with supporting victims of major disasters since the attack on the World Trade Center in 2001.
The deadline for submitting requests to participate is 25 June.
More information about the contest can be found at www.ted.europa.eu (2007/S 105-129759).