Track cycling Olympic champion and world record holder Anna Meares has been excluded from Australia's team for the world championships, casting doubt on her chances of making the Beijing Olympics.

Meares was named in Australia's provisional squad for the championships in Manchester, England, but has been dropped after breaking a bone in her neck in a horrific crash at a race in Los Angeles in January.

The omission is the latest blow for Meares, who has been forced to switch to the sprint events after her preferred discipline, the 500 metres time trial, was cut from the Olympic programme and replaced with BMX.

Kaarle McCulloch was instead picked to contest the sprint events in Manchester.

Meares, who returned from the U.S. in a wheelchair and wearing a neck brace, last month started walking again and her coach said at the time he expected her to be back on the bike in March and fit for Beijing.

The youngest daughter of a Queensland coalminer, Meares burst on to the international stage when she won the 2004 world championship in Melbourne.

Her elder sister Kerrie was favourite to take the title but had to pull out when doctors told her she risked permanent back damage if she did not undergo immediate surgery after tumbling over the handlebars in a race in Russia.

Meares took her place and duly won the world crown. She then broke the world record to add the Olympic title later that year but almost quit the sport in 2005 after suffering a bulging disc.

She made a successful comeback in 2006, winning the Commonwealth Games gold and breaking her own world record.

Meares then set another world mark to win her second world title in 2007.

The world championships in Manchester run from March 26-30.

Reuters