A mobile NSW Police camera has been slammed by Sydneysiders after it was embarrassingly defaced.

The graffiti-emblazoned security camera unit was spotted in Hyde Park, in the heart of the city centre, on Thursday afternoon.

"Free Asher," the graffiti read on a camera designed to deter crime and anti-social behaviour.

It is not clear who the graffiti is referring to.

NSW Police confirmed to SkyNews.com.au in a statement that the unit is "a mobile NSW Police camera used during operations and is part of the police operation for the weekend’s protest activity".

Palestine Action Group have confirmed a rally is scheduled to go ahead in Sydney on Sunday.

The camera was positioned next to the Archibald Memorial Fountain, front of a backdrop of St Mary's Cathedral, which has been a frequent m

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