The show director for the Tokyo Olympics opening ceremony has been fired on the eve of the event over a decades-old skit referencing the Holocaust, in the latest blow for organisers of the pandemic-delayed Games.

Kentaro Kobayashi's comments in a video of a comedy sketch from 1998 emerged online overnight and sparked shock from some in Japan.

"It came to light that during a past performance, (he) used language that mocked a tragic fact of history," Tokyo 2020 chief Seiko Hashimoto told reporters.

"The organising committee has decided to relieve Kobayashi of his post," she added.

In a statement, Mr Kobayashi apologised, describing the skit as containing "extremely inappropriate" lines.

"It was from a time when I was not able to get laughs the way I wanted, and I believe I was trying to grab people's attention in a shallow-minded way."

Mr Kobayashi, a well-known figure in theatre in Japan, is the latest member of the opening ceremony team to depart in disgrace.

The creative director for the opening and closing ceremonies, Hiroshi Sasaki, resigned in March after a comment on a female comedian.

And on Monday, a composer for the ceremony stepped down following an outcry over old interviews in which he described abusing schoolmates with disabilities.

A four-minute musical piece he composed was removed from the ceremony, but organisers left it unclear how Mr Kobayashi's firing might affect the event.

"We're still considering how to hold the opening ceremony tomorrow," Ms Hashimoto said.

"I want to reach a conclusion as quickly as possible."

Details of the opening ceremony have been kept under wraps, and strict coronavirus rules mean only around 950 people will be in the stands of the 68,000-capacity Olympic Stadium for the extravaganza.

Tokyo 2020 has been plagued by a series of gaffes and missteps by Olympic officials, including Hashimoto's predecessor Yoshiro Mori, who resigned after claiming women speak too much in meetings.