Darren Wilson: I have a clear conscience over Michael Brown shooting

The police officer who shot dead an unarmed black teenager has said he has a clear conscience over his actions, claiming he would not have done anything differently.

A grand jury decided not to press charges against Darren Wilson who killed Michael Brown in August in Ferguson, Missouri, sparking weeks of violent protests.

Speaking publicly for the first time since the fatal shooting, Wilson told ABC News that he feared for his life during the altercation with Brown.

Wilson said he was subjected to a "barrage of swinging, grabbing and pulling" by Brown who he claimed threw the first punch.

"I just felt the immense power that he had. And then the way I've described it is it was like a five-year-old holding on to Hulk Hogan [the professional wrestler]. That's just how big this man was."

He revealed that Brown's shooting was the first time he had used his gun as a police officer.

Describing the lead up to the moment he pulled the trigger, Wilson said: "I take out it out [his gun], I point it at him and I said 'get back or I'm going to shoot you'.

"He immediately grabbed the top of my gun and said 'you're too much of a p**** to shoot me'.

"While he's doing that I can feel his hand trying to come over my hand to get inside the trigger guard and try and shoot me with my own gun.

"And that's when I pulled the trigger for the first time."

Wilson also denied suggestions that Brown had his hands up when he was shot.

"If I don't [shoot Brown], he will kill me when he gets to me," he said.

He said Michael Brown's race had no influence on his decision to shoot the 18-year-old.

Asked if there was anything he could have done differently to prevent the killing, Wilson replied: "No".

"The reason I have a clean conscience is because I know I did my job right."