A violent criminal who attacked another inmate after taking legal highs in prison has been given a life sentence.

Sean Wilson, 29, pounced on Christopher Dickson in Glenochil jail in March last year.

It was claimed there had been previous "ill feeling" between the men.

Wilson had pled guilty to striking Dickson on the head with a "sharp implement" during an earlier hearing at Alloa Sheriff Court.

But the case was sent to the High Court in Glasgow for sentencing due to Wilson's lengthy list of convictions.

These included a five year jail term in 2010 for serious assault and a further four years for a similar crime in 2014.

Lord Woolman imposed an Order for Lifelong Restriction.

He also told Wilson he must serve at least 22 and a half months for the prison attack.

The judge said a pre-sentencing report concluded Wilson remained a "high risk".

Lord Woolman added the punishment part was the "bare minimum" he would spend behind bars and it was up to the Parole Board when he is freed.

John Keenan, defending, said Wilson had been abusing legal highs when he struck Dickson.

The "psychoactive" substances had apparently made him "paranoid and suspicious".

The lawyer also said Wilson had previously shown "very limited co-operation" for treatment or courses to help with his issues.