Paris, who staged the Games in 1900 and 1924, London, the hosts in 1908 and 1948, and Moscow, venue for the 1980 Olympics are among the nine.

The other six candidates are Rio de Janeiro, Madrid, New York, Istanbul, Leipzig and Havana.

Paris and London are the bookmakers' favourites at around 7-4 to win the bidding when the IOC makes its choice in Singapore in July next year.

Both cities will also give their answers on Friday to 25 questions from the IOC in presentations from the first floor of the Eiffel Tower and the Royal Opera House respectively.

The questions cover overall concept, political support, finance, accommodation, traffic, infrastructure and security.

Over the next two months the IOC's Evaluation Commission will visit the candidate cities to prepare a short list. Further evaluation visits will take place in a year's time with a final report in May next year.

The website gamesbid.com, which used a formula to correctly forecast Beijing would win the 2008 Games, places Paris ahead of Rio in its ratings with London a close third.

Paris staged the World Athletics Championships last August and the country successfully hosted the 1998 soccer World Cup. The bid has full government support while Europe is due to host the Games again after the 2000 Sydney Olympics and the 1996 Atlanta Games.

One early attraction for the Rio bid appears to be the time zone, which is favourable for US TV viewers and the major network NBC. The Games have never been staged in South America.

London retains a sentimental attraction value but major concerns remain over the transport system.

Istanbul, a perennial bidder, is fourth on the gamesbid.com ratings ahead of New York.