IOC President Thomas Bach told the head of the organizing committee to finalize the plan before an IOC meeting in late July, Toshiaki Endo, the newly appointed minister in charge of the 2020 Tokyo Olympics, said at a press conference on Tuesday.
The Japanese government said on Monday it expects the overall costs of building the new National Stadium, also the showpiece venue for the 2019 Rugby World Cup, to soar to $2 billion, up from the original estimate of $1.3 billion.
The Tokyo municipal government has been bickering with the central government over how costs will be shared.
Tokyo Olympics organizers hoped costs could be reduced, but a decision to stick with the original design by British-Iraqi architect Zaha Hadid means costs can't be cut.
Two massive arches that form the backbone of the stadium's roof, a feature that critics blamed for raising construction costs, will remain part of the design.
To slash construction and other costs, officials have proposed delaying the building of a retractable roof until after the Olympics, and making 15,000 out of the 80,000 spectator seats temporary.
Construction will likely begin in October.
The government is considering ways to generate funding.