A teenager accused of murdering schoolboy Bailey Gwynne wiped blood from his hands with a tissue in the moments after the stabbing, a court has been told.

The 16-year-old was anxious and agitated as he told Cults Academy deputy head teacher David Strang that he had "stabbed someone", the High Court in Aberdeen heard on Wednesday.

Mr Strang, who has been teaching for 28 years, was giving evidence at the murder trial of the teenager, who cannot be named for legal reasons.

He told the court the accused wiped blood off his hands in his office before phoning his parents to tell them what had happened.

Mr Strang said: "[The accused] was anxious, agitated. There were times when he got upset and put his head in his hands. He wiped the blood off his hands with a tissue.

"[The accused] handed over a knuckleduster from his pocket. He said he had stabbed someone.”

Earlier in the day, a witness who described himself as a "close friend" of the accused, told the court he had seen his friend with a knife "maybe 25 times" before the fatal stabbing.

The 16-year-old witness, who cannot be named for legal reasons, also said he had seen the teenager with knuckledusters “40, maybe 50 times” before the attack on October 28 last year.

He told the murder trial: "He thought [the knife] was cool. I said not to bring it to school."

Bailey, 16, died of his injuries at Aberdeen Royal infirmary following the incident at Cults Academy last year.

He suffered a stab wound to the heart during a fight with a 16-year-old boy, according to a joint minute read out to the court on Tuesday.

The witness said the fight that resulted in Bailey’s death began after the 16-year-old exchanged heated words with the accused following a row over a packet of biscuits.