A man's nose was left hanging off after his flatmate attacked him with a meat cleaver, a court has heard.

Tomas Bouska, 34, of Birkhall Road in Catford, attacked Nicholas Hill inside their shared home before chasing him onto the doorstep where he continued to rain down blows, the jury at the Old Bailey was told.

The court heard the attack happened despite the victim alerting the local mental health authority about his flatmate's behaviour in the period leading up to the attack and Mr Hill shouted "Tomas stop, you are killing me" as Bouska tried to strangle him until he broke free and managed to get back inside the house.

The defendant managed to get in through the back door and a panicked Mr Hill, 46, was unable to open the front door in time and the attack continued.

It only stopped when Mr Hill managed to run to a neighbour's house, locking Bouska outside until police arrived on August 5 last year.

Mr Hill suffered multiple wounds, which included skull fractures, cuts across his face and body and had to have his nose stitched back on to his face, the Old Bailey heard.

Catherine Farrelly, prosecuting, said: "The defendant tried to kill Mr Hill in what we say was a sustained and frenzied attack using a meat cleaver."

In the months leading up to the attack, Mr Hill had passed on his concerns about Bouska's mental health to the South London and Maudsley Community Mental Health Team.

Bouska claimed his bedding was being poisoned by his former flatmate, a friend of Mr Hill's called Stuart, and Mr Hill was in on the plot.

Bouska also told him he planned to poison Stuart and had bought a knuckle duster from eBay, it was said.

Ms Farrelly told the jury: "Mr Hill repeatedly emphasised his concern to various authorities."

On the day of the attack, Mr Hill tried to speak to Bouska about his health and "continuing strange behaviour", the prosecutor said.

But during the 7am chat Bouska became aggressive, and went into the kitchen and grabbed a meat cleaver, the court heard.

Ms Farrelly went on: "He then approached Mr Hill and then repeatedly used the meat cleaver in order to hit Mr Hill about the head and the back.

"As he was doing so, Mr Hill tried to flee towards the front door of the property in order to escape the attack.

"Despite the fact that Mr Hill was running away, the defendant continued to pursue him.

"The two of them wrestled inside the property.

"Eventually he, Mr Hill, managed to get outside of the property. But again he was still pursued.

"The two of them continued to wrestle outside of the front door, with the defendant trying to strangle Mr Hill by wrapping his arm right around the neck."

Ms Farrelly said: "Mr Hill was frantically trying to open the latch of the front door to escape, but in his panic he couldn't get the front door to open.

"The defendant descended upon Mr Hill, repeatedly raining blows using the meat cleaver.

"Mr Hill managed to open the front door and run out into the street, followed by the defendant who continued to attack.

"Mr Hill had blood pouring down his face and into his eyes. And he could hear someone calling out to him, telling him to run.

"And so he ran as fast he could into a neighbour's house, and sought shelter here.

"He could still hear the defendant trying to force his way through the front door."

A neighbour described Mr Hill's nose as "hanging away from his face" and the meat cleaver being covered in blood, the court heard.

Another said he saw Mr Hill wearing ripped pyjamas covered in blood, while Bouska attacked him in a "swinging and chopping motion".

Police arrived at the scene and managed to restrain and arrest Bouska.

Mr Hill was taken to hospital where he had surgery for his multiple wounds.

Giving evidence, Mr Hill said: "He believed that Stuart was poisoning the bedding, and was concerned that I was cooperating with him."

Referring to last August, he said: "I believe he had no medication.

"And I know that he did go to the doctor on Tuesday, prior to the Friday of the attack, and he came back with a prescription for paracetamol."

Turning to the day of the attack, he said: "Tomas accused me of poisoning him.

"Tomas then got enraged, and said he was going to kill me because I was too close to Stuart.

"At which point he pushed me to the conservatory, and ran to the kitchen drawer and started hitting me in the head with a meat cleaver.

"He said, 'look, I am too close to Stuart and I am involved in poisoning him'.

"It was a very forceful blow. It was disorientating. I felt like I was falling down. I felt that my life was in danger."

The prosecutor said Bouska does not deny he meant to cause really serious harm, but the issue was whether the intention went beyond that.

Bouska denies attempted murder.

The trial continues.