Full crowds in Tokyo for this year's World Athletics Championships can make up for fans being locked out of the city's pandemic-postponed Olympics in 2021, the event's CEO has said.

The Tokyo Games took place a year later than planned and behind closed doors in a bid to halt COVID-19 infections, creating an eerie atmosphere in venues and forcing fans to watch the action at home on TV.

There will be no such restrictions when the Japanese capital hosts the World Athletics Championships in September at the National Stadium, which seats over 65,000 and was the main venue for the Olympics.