As it happened: Violence erupts in Sydney over anti-Islam film

Violence erupted in central Sydney as hundreds of Muslims protested against a controversial film about the Prophet Mohammed.

It is the latest in a series of demonstrations that have killed at least six people in the Middle East.Protestors have also marched through London.

The wave of protests spread to Sydney's CBD yesterday afternoon, beginning outside the United States Consulate and spreading through the city's streets to Hyde Park.

The ABC understands the protest was sparked by a mass text message saying: "We must defend the honour of our prophet, we must act now."

NSW Police Superintendent Mark Walton said the demonstration was unorganised and some protesters "came forearmed to cause damage".

He said up to 150 police officers were called to the protest. Six officers were injured during the afternoon and two were taken to hospital for treatment.

Superintendent Walton said the protesters left the demonstration by 6:00pm.

Here is how the story developed throughout the day.

6:28pm: In related news in the United States, a California man has been escorted to an interview with federal officers probing possible probation violations stemming from the making of the anti-Islam video that triggered violent protests in cities across the world.

A Los Angeles County Sheriff's spokesman said Nakoula Basseley Nakoula - who is linked to the film's production - voluntarily left his home, accompanied by sheriff's deputies, to meet with the officers in the Cerritos Sheriff's Station.

"He will be interviewed by federal probation officers," sheriff's spokesman Steve Whitmore said.

"He was never put in handcuffs... it was all voluntary."

But he said Mr Nakoula was not in custody.

6:20pm: Here is more of what NSW Police Superintendent Mark Walton told reporters in Sydney a short time ago:

The engagement that police have arrested eight individuals for various offences including affray, assault police dog and throw a missile.

There's been two police vehicles at a minimum that have been damaged when the crowd attempted to move away as a group and contrary to police direction were asked to hold in the park and disperse in an orderly fashion.

Ultimately the group dispersed itself throughout Hyde Park and into the east Sydney area.

Unfortunately six police have been injured during the contact with this group throughout the afternoon, two of which have received treatment in hospital for minor injuries.

I think we have actually acted very professionally and responded very well to what was a completely unannounced and unorganised protest. There was no advice given to police by this group that they intended to protest and, as a result, in a very short amount of time we had a significant amount of police.

I am not sure about who might have been caught in it. But my information suggestions that some of these people came forearmed to cause damage and potentially conflict an assault with police.

There were bottles thrown, there are other implements that were used today by this crowd in their contact with the police.

NSW Police Superintendent Mark Walton

6:15pm: New South Wales Police Minister Mike Gallacher has just spoken to ABC News 24 . Here is some of what he had to say:

Police were prepared for a protest tomorrow, they had gone through the formal reporting process to get approval.

It would appear from the reports we have had, that I have had this afternoon from police, that possibly threw some form of networking, through whether it be Twitter or whatever, there's been an ability to get a large number of people into a crowd and then we saw the consequences of that fairly quickly.

The Intel is that it would appear that they were a number of people there that went there for peaceful protests. But then in amongst them were people that probably weren't there for peaceful protest, they were there for confrontation.

Police only use capsicum spray when they're under threat. They don't take it out and use it otherwise. The footage speaks for itself. People did not want to be in a confrontational action with police. Then they shouldn't have been there at the forefront in front of the police.

I think the police have responded quickly getting a significant number of people there, the good thing is that it has now dispersed.

Now what will happen is police, through their communication, with the community that have participated in this try to identify who are the sensible headed once and start to talk to them in the way that they always do.

They were the ones that were expected to be participating in tomorrow's protest rally, sadly this one has been hijacked by people that are more about confrontation and providing colour and movement. We've seen that some of the - we're seeing some of the angry scenes that were taking place in the CBD.

Today wasn't a lawful protest and there may well be that some people take it upon themselves to again turn up on Sunday in a Martin Place or any other part of the city, then be rest assured the police planning is now under way tactically in relation to that. It's quite a worrying situation.

NSW Police Minister Mike Gallacher

6:00pm: Police have defended their response to demonstrations in Sydney, part of a Muslim protest against a controversial film about the Prophet Mohammed.

In a press conference, Superintendent Mark Walton said eight people were arrested during the "unannounced protest".

Up to 150 police officers attended the incident throughout the day. Six officers were injured, including two who were taken to hospital for treatment.

Two police vehicles were also damaged.

Superintendent Walton said the protesters have now "self-dispersed" throughout the city. Police remain at the scene.

5:50pm: Sydney police are holding a press conference. A spokesman said up to 150 officers attended the protest and six officers were injured. Two have been treated in hospital. Watch live here.

5.41pm: Here's a photo Josh Bavas took of the moment the protest turned violent: