A teenager accused of murder broke down in tears as he told a jury he did not realise he had stabbed his friend in the heart during a row on the street.

The youngster knifed Yousef Makki, 17, a scholarship pupil at £12,000-a-year Manchester Grammar School, in Hale Barns, a leafy village in Cheshire, on March 2.

The 17-year-old defendant, boy A, and a second youth, boy B, also aged 17, are standing trial, now in its second week, at Manchester Crown Court.

Neither can be named because of their age.

Boy A claims he acted in self-defence after Yousef pulled a knife on him and the death was an accident.

He told the jury on Thursday his memory of the fatal incident was "spotty" and he had "not been able to come to terms with what happened".

Prosecutors allege the background to the fatal stabbing was that earlier in the day, boy B arranged a £45 cannabis deal and the teenagers planned to rob the drug dealer.

But the robbery went wrong and Yousef and boy B fled, leaving boy A to take a beating, the jury heard.

Boy A then later stabbed Yousef.

He told the jury he wanted to go home after he took a beating, but the other boys tried to persuade him to stay out.

He continued: "Then I believe Yousef got annoyed with me. He's called me a pussy.

"I have got annoyed at this because I was the one got beaten, while one of my friends ran off the other just watched.

"This is when I pushed Yousef, just out of frustration."

He said Yousef then punched him in the face.

He continued: "I was not really expecting it. I have then looked back up, Yousef was quite annoyed with me at this point I believe I saw him, he had taken his knife out, looked like he was going to hit me again, saying, 'Come on! Come on!"

At this point the defendant's face reddened and as he dabbed tears from his eyes.

He continued: "I don't know how I was feeling at the time. I probably just didn't want to get beaten up again. I was quite on edge.

"So then I started to take the knife out of my pocket. This is in a matter of seconds.

"I do know what I did. I don't know how it came together.

"Trying to get my knife. I'm a bit disorientated. I can't remember if Yousef laughed a bit or said something.

"I have got more annoyed. I have taken it out straight away, I don't really know what I did, kind of lifted my arm up.

"I didn't realise anything had happened at first. Yousef took a step back."

Alastair Webster QC, defending boy A, said: "Did you appreciate the knife had gone into him?"

Boy A replied: "No. I started to walk away. Then Yousef called out saying, 'He's stabbed me' or 'I've been stabbed'.

"At that point I went into a bit of a panic."

Mr Webster asked him: "If he had not come towards you with a knife, would you have taken it out?"

Boy A replied: "No, I don't think I would."

Mr Webster continued: "Did you intend to cause serious harm? Did you intend to stab him?"

"No," the defendant replied. "I didn't think I had stabbed him. I thought I had cut his shoulder, I didn't feel any resistance."

Under cross-examination, Nicholas Johnson QC asked the witness: "Do you remember the evidence of the pathologist? There was bruising around the knife wound because the hilt had gone into Yousef's chest?

"If he's right about that, you must have felt something?"

Boy A replied: "Er, from my recollection, I don't remember feeling anything."

He admitted telling lies to police scrambled to the scene on Gorse Bank Road, that he did not know what had happened.

"I didn't really know what to do. Once I said that, I kind of kept on going with it," he said.

Under questioning by Eleanor Laws QC, defending boy B, he denied trying to absolve himself of blame or deflect some responsibility on to his co-accused.

He replied: "I know what I have done, I think about it every day. I don't blame him any more or myself any less."

Boy A denies murder, but has admitted perverting the course of justice and possessing a flick knife.

Boy B is accused of lying to police at the scene about what had happened and what he had seen. He denies perverting the course of justice. He too has admitted possessing a flick knife.

Both youths deny a charge of conspiracy to rob the drug dealer.

The trial continues.