An artist’s impression of the proposed facilities in east London for the Olympic games in 2012. Photograph: Andrew Hilton/Hayes Davidson/PA

The organisers of the 2012 London Olympics face the toughest economic circumstances outside of a state of war to put on the games, an influential member of the International Olympic Committee has said.

Kevan Gosper, an Australian who is the head of the IOC’s press commission, gave the warning to Sebastian Coe, the chairman of the 2012 organising committee, at a question-and-answer function in the capital yesterday.

Gosper, a vice-president of the Sydney Olympics organising committee, said: “I think you and your team face the toughest time – short of wartime – to get the project to 2012.”

Lord Coe responded by saying that the games could help London and Britain cope with a recession.

Coe’s comments echoed those of the mayor of London, Boris Johnson, who said earlier this month that the capital was “extremely fortunate” to be hosting the games in the current economic climate.

Coe said last night that Britain ought to be on the “front foot” because the games were a “very good project” to have at the moment.

He said: “More than 3,500 people are on the [games] building site currently, of which 10% had been permanently unemployed. The work safeguards these jobs in an economic downturn.

“Billions of pounds of contracts are available, so this is a very good project to be having at the moment.

“No one would have chosen this [downturn], but the games could account for 6-7% of economic activity in this city over the next five years, not to mention the impact it could have on other parts of the country.

“That’s why we should be on the front foot; in good times or in bad this is a project that really has an extraordinary impact.”

Jacques Rogge, the president of the IOC, said that, although the financial crisis posed a challenge for organisers, he was confident the games would survive the test.

Tessa Jowell, the Olympics minister, raised eyebrows earlier this month when she admitted that the government would probably not have bid for the games if it could have foreseen the recession.

Rogge said that the games had survived global economic slumps in the past and pointed out that London would be less dependent on huge building projects than this year’s Beijing games.

In his speech to the Royal Society for the Encouragement of Arts, Manufactures and Commerce, he said: “I am conscious that we come out of the enormous success of Beijing into difficult economic times.

“Well, the games have survived difficult times before. They have survived and thrived because of what they mean to people all over the world. The games remind us that the transient difficulties of life can be overcome through hard work and determination.”

International Olympic chiefs are in London this week for four days of talks on the lessons that can be learned from the Beijing games.

Officials from Beijing are sharing their experiences with organisers from London, Vancouver (host of the 2010 winter games), Sochi (the Russian city hosting the winter Olympics in 2014) and the 2016 candidate cities.

Rogge said that the IOC’s decision to slim down the games following the Olympic games study commission report of 2003 would help London to cope with economic difficulties.

The report had made a series of recommendations to limit the size, cost and complexity of future games, he said.

“London has learned from this, and it will build its games around legacy and sustainability.”

He added: “Each games are unique. It is not the amount of money spent that determines how good a games is, it is also the unique and inspiring atmosphere created within the city. I’m sure London will do very well there.”

Rogge used his speech to praise the record-breaking medal haul of the British Olympic team in Beijing and said that the challenge now was to inspire a generation of couch potatoes to take up sport.

guardian.co.uk