A prisoner brutally attacked a hungry fellow inmate who pestered him for food.

David Robertson left Ian Hislop with a collapsed lung as well a fractured cheekbone and jaw after turning on him at HMP Low Moss in East Dunbartonshire on March 9 this year.

Robertson, 36, punched Hislop so hard, he ended up with a broken finger himself.

Both were serving life sentences at the Low Moss.

Robertson - who had convictions for violence and wilful fire-raising - was given an Order for Lifelong Restriction in 2009.

Hislop was jailed for a minimum 15 years in 2008 for the murder of a man in Glasgow's Shawlands.

Prosecutor Lindsey Dalziel said Hislop had been in Robertson's cell before being spotted leaving injured and limping.

She added: "He told staff he had been in a fall."

Robertson was later quizzed and admitted he had punched Hislop, who he described as being under the influence of drugs.

He had ordered the killer not to get back up, but when he did, raging Robertson stated he "set about him".

The court heard Hislop could have died without urgent treatment.

Euan Dow, defending, said there had been no issues with the men in the past.

The advocate: "It was obvious Hislop was heavily under the influence.

"He was asking did he have any food that he could provide him.

"Robertson does not take illicit substances. He was annoyed at him and his persistent demands towards him."

The hearing was told Robertson has been behind bars since around 2007.

He pleaded guilty to assaulting Hislop to his severe injury, permanent disfigurement and danger of life.

Lord Clark sentenced him to four years to run alongside the jail-term he is currently serving.