The designer of the logo for the 2020 Tokyo Olympics on Friday denied claims of plagiarism after his emblem triggered threats of possible legal action in Europe.

In the latest public relations blow to Tokyo after plans for its $2 billion Olympic stadium were ditched, controversy raged over similarities between the Olympic emblem to the logo of a Belgian theatre and a separate Spanish design.

Belgium-based designer Olivier Debie told AFP he was "puzzled" by events and was considering taking the matter to court, citing the resemblance to his design for the logo of a theatre in Liege.

But Japanese artist Kenjiro Sano protested his innocence.

"I had absolutely no previous knowledge of the design in question," he said in a statement.

"I certainly did not refer to it when creating my design. I have attempted to pay homage to the Tokyo 1964 Games emblem and thought long and hard about which elements I could incorporate to create distinctively Japanese emblems."

Currently overseas on business, Sano added: "I look forward to further explaining how I created the Tokyo 2020 Games emblems when I return to Japan."

Japanese Olympic organisers insisted on Thursday that they had exercised due diligence.

"Tokyo 2020 went through a regular verification procedure and chose the logo after a long, comprehensive and transparent process," organisers said.

"Prior to unveiling the emblem, the IOC and Tokyo 2020 conducted extensive research on trademark protections. We did not identify any particular issues."

The logo, unveiled last week, is based around the letter "T" -- for Tokyo, tomorrow and team with a red circle representing a beating heart.

To add insult to injury for Tokyo, subsequent claims emerged that the emblem also bore remarkable similarities to a design by Barcelona-based firm Hey Studio created in support of Japan, following the deadly tsunami in 2011.

Debie took to social media to criticise the Sano's work, tweeting: "Theatre Liege vs Tokyo 2020... #plagiat?", using the French word for plagiarism.

Contacted by AFP, Debie's lawyer Philippe Mottard and the theatre's attorney Alain Berenboom said they wanted to "get the use of the logo stopped" and planned to submit a letter to the International Olympic Committee (IOC) on Friday seeking to halt its use.

Failing that, they planned to file a formal complaint to a Belgian court.

The theatre's logo features a similar shape in white against a black background.

Japanese officials are still smarting from the fiasco over the Olympic stadium two weeks ago when Prime Minister Shinzo Abe ordered plans to be torn up amid growing anger over its price tag.
Source: AFP