TOKYO (AFP) - Construction of the main stadium for the Tokyo 2020 Olympics officially started on Sunday (Dec 11), more than a year after the original blueprints were torn up following public outcry over skyrocketing costs.

The stadium is due to be completed by the end of November 2019, five months behind schedule.

"I believe, after four years, many athletes will challenge their physical limits at this stadium and empower spectators and the society," Prime Minister Shinzo Abe said at a ceremony to mark the start of building work.

Japan approved the new stadium plans in September after Abe scrapped the initial design by the late Iraqi-British architect Zaha Hadid as costs soared beyond US$2 billion (S$2.9 billion).

The 149 billion yen (S$1.8 billion) price tag for architect Kengo Kuma's proposal comes in just under the cap for the contractors, led by construction giant Taisei Corp.

The new venue is being built on the site of the former national stadium which was used for the 1964 Tokyo Olympics.

Concerns that ballooning costs could hit a staggering US$30 billion - four times the initial estimate and almost triple that of the 2012 London Olympics - have forced organisers to rethink plans for several venues.

Tokyo Governor Yuriko Koike announced recently that the host city would build a new aquatic centre with 15,000 seats, costing less than the original design for a 20,000-seat arena.

Plans to move the canoeing venue outside Tokyo have also been dropped.