The jury in the trial of an alleged extremist accused of plotting a cyanide attack ''for the Aryan people'' has been discharged after it failed to reach a verdict.

Mark Colborne, from Southampton, was on trial at the Old Bailey accused of preparing terrorist acts before his arrest on June 3 last year.

The court heard that the 37-year-old made notes in his diary of a plan to shoot the Prince of Wales with a high-powered sniper rifle, and bought the ingredients for cyanide over the internet.

The defendant, who the court heard likened himself to Norwegian terrorist Anders Breivik, also stockpiled dust masks, metal filter funnels, plastic syringes and latex gloves and acquired manuals entitled Assorted Nasties, Silent Death and The Poor Man's James Bond, jurors were told.

His half-brother contacted police after he uncovered chemicals and papers detailing Colborne's racial hatred stashed in his bedroom at the family home.

But in his defence, Colborne denied that he was actually planning an atrocity and dismissed extracts from his diary as just ''angry rants'' made while he was off medication for depression.

The jury retired last Thursday but after three days deliberating could not agree on a verdict and was discharged.

The prosecution indicated that it would be seeking a retrial on a date to be fixed before the Recorder of London.