Tokyo 2020 Olympic organisers on Friday unveiled a shortlist of four new logos more than six months after the original choice was scrapped over an embarrassing plagiarism scandal.

Nearly 15,000 suggestions were submitted, including over a thousand by Japanese schoolchildren, organisers said.

The four finalists feature, respectively, a indigo-coloured Japanese traditional checkered pattern, a morning glory floral design, an image of an athlete crossing a finish line, and a multi-coloured ring symbolising harmony, according to the organisers.

The identities of the designers were not released. The organisers said that the winning design would be announced on April 25.

The designs are at the top while at the bottom of are the words "Tokyo 2020" below which are the five interlocking Olympic rings.

The artwork for the Paralympic Games, meanwhile, represent slight variations of those for the Olympics and were created by the same designers.

"I'm proud to say that these are the best works at this point," Ryohei Miyata, head of the Tokyo 2020 emblem committee, told a news conference, stressing their originality.

The shortlisted designs were checked against registered trademarks in cooperation with the International Olympic Committee, Miyata said.

Last August, Tokyo organisers were forced to ditch a logo by Japanese designer Kenjiro Sano following allegations it too closely resembled that of a theatre in the Belgian city of Liege created by designer Olivier Debie.

Officials insisted their decision had not been in response to a lawsuit filed by Debie but slumping public confidence as Tokyo organisers lurched from one crisis to another. Sano has denied any plagiarism

The logo controversy came shortly after Japanese Prime Minister Shinzo Abe pulled the plug on plans for a $2 billion Olympic stadium amid public anger over spiralling costs.

In the face of mounting criticism, organisers opened the selection process to the public -- rather than limiting it to a small group of professional designers -- in a bid to improve transparency.

"We put the first priority on participation by as many people as possible and a transparent selection process," Miyata said.