Tokyo 2020 bosses vowed Monday there would be no let-up in their Games preparations, as the president of the IOC said some previous host cities were less prepared even with three months to go.

Yoshiro Mori, head of the 2020 organising committee, said they had won strong backing from Olympic officials in Tokyo for crunch meetings — with some 600 days to go until the Opening Ceremony.

“There were so many words of praise but we will not be conceited about this. I think we should not relax,” said Mori, noting they would undoubtedly face “difficulties and uncertainties” in the run-up to the Games.

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After a shaky start, Tokyo 2020's preparations have largely been brought back on track and with venue construction broadly on schedule, the last-minute scramble to complete stadia seen at previous Games has so far been absent in the Japanese capital.

IOC head Thomas Bach said no city had ever been so well-prepared as Tokyo at the same stage.

“In some of the cities — even in most — we had to organise crisis meetings with the Executive Board a couple of months before the Games and some of them were maybe not where you are today already even three months before the Games,” said Bach.

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Nevertheless Tokyo 2020 still faces a host of potential pitfall, including how to deal with the sweltering summer heat and keep a lid on the budget.

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Tokyo 2020 officials have admitted that some measures introduced to beat the heat have placed added pressure on costs but stressed the next version of the budget due later this month will not exceed the $12.6 billion earmarked in the most recent version last year.

Recent months have been marked by wrangling between 2020 organisers and the central Japanese government over what should count as an Olympic expense.

In October, Japan's audit board said spending by the central government was well over what was originally budgeted but organisers hit back, saying many costs included in their report were not directly Olympic-related.

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The head of the coordination commission liaising between Tokyo 2020 and the Olympic movement said the public needed to understand there was “a clear delineation between the operating costs of these Games and the legacy investment that's taking place for these Games in infrastructure.”

“The message that we have to get through is that the operating budget will be covered. There will be no drain on the public purse,” said John Coates.