Chairman of the London 2012 Olympic bid, Sebastian Coe, answers questions at a news conference in London on Tuesday. (Reuters)

The unfolding story of who will host the 2012 Olympic Games turned into a tale of two cities on Monday after a crucial report by assessors from the International Olympic Committee (IOC) found little to separate London and Paris.

A month before the decisive ballot in Singapore, the rival capitals emerged as the strongest contenders in a 119-page document intended as a guide for the 117 IOC members eligible to vote. The three remaining candidate cities, Moscow, New York and Madrid, saw their chances of success slip.

Thirteen months after Lord (Sebastian) Coe took over from Barbara Cassani as bid leader, London has addressed IOC concerns over transport, venues and government backing and turned itself into a credible choice. Coe, a double Olympic champion, said that the report was a “springboard” for continued campaigning in the run-up to the vote on July 6.

“A lot of hard work has paid off,” he said. “This was never going to be the management of ‘It’ll Be Alright On The Night. This was choreographed to within an inch of its life’.”

The report was written after a four-day site visit in February by an IOC evaluation commission led by Nawal El Moutawakel, who won 400m hurdles gold for Morocco in 1984.

During the visit, made necessary by strict IOC rules on ethics after the Salt Lake City bribery scandal in 2000, the team was whisked around present and proposed venues and driven in Range Rovers through the Channel Tunnel rail link between Stratford and St Pancras to illustrate the transport blueprint.

The impact of the carefully planned tour was evident in the report, the first of its kind for an Olympic bidding process. An interim IOC assessment last May condemned London’s transport system as “often obsolete”.

This time, the evaluators noted substantial investment in transport that, if delivered as promised, would meet Olympic requirements. They also accepted estimated bus speeds and journey times, an area of dispute at the interim stage.

“London would be capable of coping with Games-time traffic,” they said.

The report praised London’s use of existing world-class venues such as Wimbledon for tennis and Dorney Lake, Eton, for rowing. Twenty-two venues will be within 28 minutes of the Olympic village in East London.

The biggest caveat attached to praise for London concerned the fact that much of the bid is still a paper vision compared with Paris. Thirty-six per cent of venues need to be built, including an 80,000-seat Olympic Stadium.

In the context of the saga that is the rebuilding of Wembley Stadium, which would host the Olympic football final, the concerns about London’s ability to deliver the world’s biggest sporting event are clear.

“The magnitude of the project, including the planned upgrade and expansion of transport infrastructure, would require careful planning to ensure all facilities and rehabilitation projects were completed on time,” the report said.

Paris received no real criticism, veiled or otherwise, with its report littered with adjectives such as “excellent” and “exemplary”. The city has proven experience of hosting similar events, including the football World Cup in 1998.

Paris also has stronger public support, according to the last official IOC poll, with 85 per cent of the city’s population in favour and 79 per cent elsewhere in France. London’s support was 68 per cent in the city and 70 per cent outside, but has improved since the poll in December, according to independent research.

The undertones of the evaluation team’s report suggest Paris is the safer bet, but IOC members are in no way bound by its findings. National allegiances and the order in which the five cities are eliminated in each voting round are key.

The Latin American countries, whose first vote would probably have gone to Madrid, could provide the vital swing.

Paris is still the bookmakers’ favourite. Ladbrokes have cut their odds from 5-1 on to 6-1 on, with London maintained at 7-2. Madrid, ranked second by the IOC ? ahead of London ? at the interim stage, drifted from 12-1 to 16-1, New York from 20-1 to 33-1 and Moscow from 66-1 to the 100-1 rank outsider.

“It is a two-horse race, with Paris the strong front-runner,” a Ladbrokes spokesman said. “London can be encouraged, however, that favourites have a bad record of securing the Games. The odds now suggest that Madrid, New York and Moscow are all but out of the race.”