An extremist who posted a YouTube video warning of a terror attack on the wedding of the Duke and Duchess of Cambridge will be sentenced today after being convicted of terror offences.

Afsor Ali, 27, was found guilty of three out of four counts of possessing terrorist material following a trial at the Old Bailey.

Ali, of Bethnal Green, east London, had earlier admitted possessing someone else's UK passport in an unsuccessful bid to flee on the Eurostar to Paris in March.

Jurors were told Ali was first arrested in December 2011 when he took part in a protest against American drone attacks in Pakistan alongside members of the banned group Muslims Against Crusades outside the US embassy.

He was released without charge but during the investigation an MP3 player was seized with a laptop and external hard drive taken from his home during a search.

When they were examined, they were shown to contain documents that were useful to terrorists, the court heard.

When police searched his home months later they found his new computer also contained extremist material, jurors were told.

During the trial, prosecutor Oliver Glasgow told the court Ali had promoted extremism in YouTube videos under the alias Asad Ullah.

In a clip from 2012 he warns the viewer not to attend the royal wedding because of a terror attack.

In another clip, Ali hails the 9/11 attack as "an historic event", the court heard.

The jury was also told that in addition to documents he was charged with having, police recovered two personal recordings of a telephone call between the defendant and the radical Islamist Shaykh Omar Bakri Mohammed.

And he had a transcript of a speech given by Omar Bakri in which he seeks to legitimise suicide bombings.

On November 29 2012, Ali was charged with possession of documents or records containing information of a kind likely to be useful to a person committing or preparing an act of terrorism contrary to Section 58 of the Terrorism Act 2000.

He was found guilty of possessing two electronic files containing Inspire - the al Qaida magazine - and an electronic file containing 39 Means to Serve and Participate in Jihad. He was found not guilty on a fourth count.

Ali, who is in custody, will be sentenced by judge Charles Wide QC at the Old Bailey from 10am.