The 23-year-old from Helensburgh was racing on day one of the Supercross in Bathurst on Saturday when he was injured.

He was taken by helicopter to Canberra hospital in a critical but stable condition, according to a statement on the BMX Australia website.

Sakakibara fell on the second corner during his opening round heat and was treated on site by paramedics and a doctor before being taken to hospital.

The event was called off for the day after the men's first round because of wind and rain.

Sakakibara and his younger sister Saya aim to make their Olympic debuts in Japan, where he spent part of his childhood after being born on the Gold Coast.

He started racing BMX at the age of four before his family moved to Toyko in 2000.

Sakakibara continued to show promise in the sport, claiming the Japanese national championships in 2004, 2005 and 2006 and finishing sixth in the world championships.

The family returned to Australia 12 years ago where he joined the Southlake Illawarra BMX Club, the base for a string of national and state titles.

Australian Associated Press