The personal assistant of MP Jo Cox has described the moment an alleged extremist launched his gun and knife attack shouting "Britain First".

Fazila Aswat was with the Labour politician when Thomas Mair, 53, allegedly stabbed and shot her in the street days before before the EU referendum in June.

Giving evidence in his Old Bailey murder trial, Ms Aswat told jurors how she pulled up in a silver Vauxhall Astra with mother-of-two Ms Cox and another colleague outside the library in Birtsall, West Yorkshire, where she was due to hold a surgery on 16 June.

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She said: "So I got out of the car. I was still on the roadside. Jo walked over to the side of the pavement and my colleague walked a few steps closer up. In that instant our lives changed forever.

"The next thing I saw was Jo on the floor and there is a man stood over her with a knife and I think that's when I knew it was completely wrong.

"At that time - panic. I started to shout 'somebody help, help'. There was a gun, there was a knife and she was on the floor. I can remember the movement, it was really fast so I can't say which part of the body was targeted."

Ms Aswat said she did not remember Mair saying anything during the attack but that he did so as the MP lay dying.

She said: "It was at the very end, when he stood up and said 'Britain first, this is for Britain, Britain will always be first'."

She said that she had told the MP to run away between attacks but Ms Cox replied: "Fazila, I can't run, I'm hurt."

Jo Cox shooting - pictures of the crime scene Show all 7 1 /7 Jo Cox shooting - pictures of the crime scene Jo Cox shooting - pictures of the crime scene Media reports said Jo Cox, 41, who is a lawmaker for the opposition Labour Party, had been attacked as she prepared to hold an advice surgery for constituents in Birstall near Leeds REUTERS Jo Cox shooting - pictures of the crime scene A handbag and shoes lie on the ground as police cordon off an area after Jo Cox, was shot and stabbed by an attacker at her constituency in Birstall Getty Images Jo Cox shooting - pictures of the crime scene Medical equipment lies on the ground behind a police cordon in Birstall near Leeds REUTERS Jo Cox shooting - pictures of the crime scene Police stand behind a cordon in Birstall near Leeds. A British lawmaker Jo Cox was in critical condition after an incident in her constituency in northern England REUTERS Jo Cox shooting - pictures of the crime scene An eyewitness said the 41-year-old mother of two was left lying in a pool of blood on the pavement after her assailant struck in Birstall PA Jo Cox shooting - pictures of the crime scene Police stand behind a cordon in Birstall near Leeds REUTERS Jo Cox shooting - pictures of the crime scene Police stand behind a cordon in Birstall near Leeds REUTERS

Sandra Major, Mrs Cox's senior caseworker, who was in the car with Ms Aswat and the MP, told the court she saw a man in her peripheral vision walking past then.

She said: "He had a gun in his hand. He raised his arm and shot her in the head. It was in the area of her temple.

"She fell backwards into the ground and there was blood pouring down her face."

Asked by prosecutor Richard Whittam QC whether the attacker had said anything, she added: "It was something along the lines of 'keep Britain independent' or 'British independence'.

Ms Major told jurors that Ms Cox tried to protect her staff even as Mair was stabbing her.

She said: "He was making motions towards us with the knife and Jo was lying in the road and she shouted out 'get away, get away you two. Let him hurt me. Don't let them hurt you'.

"He started to walk away a little bit and when Jo shouted out then he came back. He shot her twice more and then started stabbing her again. She was on the floor. She didn't get up again. He was still shouting and shouting."

Mair denies Ms Cox's murder, possession of a firearm with intent to commit an indictable offence and possession of an offensive weapon - a dagger.

The case continues.