Princess Diana's former lover has appeared on Australian television to deny he is Prince Harry's father.

James Hewitt, a former army officer who served in the Queen's Life Guard regiment, was romantically linked with Diana for five years during the late 1980s before he was called up to serve in the first Gulf War. The pair met at Buckingham Palace and, in 1986, he was employed to conduct her horse riding lessons.

On Sunday, the 58-year-old appeared on Channel Seven's Sunday Night in a feature commemorating 20 years since her death.

As well as her affair with Hewitt, the hour-long special canvassed her struggles with bulimia, her admirers - including a US politician who promised to make her First Lady - and how, after seeking counsel from psychics, she believed Prince Charles was plotting her death.