A British law student accused of targeting former prime minister Tony Blair as part of a terror plot was found guilty of having a bomb-making document, it can now be reported following the conclusion of the secret trial.

A jury at the Old Bailey decided Erol Incedal, 26, did not have a reasonable excuse for possessing the electronic file on a memory card which contained instructions on how to make a viable explosive device.

But jurors failed to reach a verdict on another charge of preparing an act of terrorism with others abroad and was discharged on November 11.

The details could only be reported today after the trial judge, Mr Justice Nicol, lifted restrictions.

A retrial lasting four to five weeks was provisionally set to start on February 23 next year.

The court had heard that the 26-year-old Londoner, previously known as AB, was arrested on October 13 last year in his car near London Bridge.

Police had bugged his black Mercedes for a fortnight after he was stopped for speeding on September 30 2013.

The micro SD memory card containing the bomb-making document and another file on car bombs was found tucked into the cover of his iPhone.

Incedal, a father-of-two, admitted possessing the document and that it was of use to someone preparing an act of terrorism but claimed he had a "reasonable excuse" for having it.

He also denied preparing an act of terrorism with others by targeting individuals, such as former prime minister Mr Blair, or a wide-ranging Mumbai-style attack.

His co-defendant, Mounir Rarmoul-Bouhadjar, 26, formally known as CD, pleaded guilty before the trial started to having an identical document.

The jury was discharged after deliberating on verdicts for 23 hours and 35 minutes.