It's the elephant in the Olympic room.

As world class athletes show their stuff in Rio, vast swathes of stadiums are sitting empty as organisers fail to sell tickets to the events.

Vacant seats have been spotted at a huge range of events including the opening ceremony, water polo, beach volleyball, rugby sevens, weightlifting, tennis and gymnastics despite the drawcards of world class athletes like Rafael Nadal and US gymnast Simone Biles.

Tickets are still available for the Athletics finals at the end of next week for between $350 and $1200 Brazilian Real with even Olympic great Usain Bolt forced to encourage fans to come along with a video on his Twitter account.


The vacancies have been blamed on a combination of factors including inaccessible venues, lengthy security checks, fears over Zika, a recession in Brazil and high ticket prices.

Organisers said Brazilians are "late buyers" and 84 per cent of all tickets have been sold. They claimed some venues were hosting double-header events and guests were opting to show up for one session only.

Tickets allocated to sponsors or corporate guests who have failed to show up are in the process of being redirected to local schoolchildren. Others have suggested the low profile of sports like hockey and rugby sevens in Brazil has led to a lack of interest on behalf of locals.

Less than 500 people attended the boxing earlier this week while beach volleyball stands appeared only about 20 per cent full.

Meanwhile authorities have cracked down on ticket scalpers with a British man and his interpreter arrested and more than 1000 fake tickets seized.

Earlier in the week organisers were forced to apologise after lengthy queues and security checks led many to miss events they had planned to attend.

Spectator and Rio resident Natalia Carvalho, 28, missed seeing Brazilian gymnast Arthur Zanetti compete and said the situation ws "ridiculous".

"It's a lack of respect for the fan that bought tickets. It's a shame," she said.