The New South Wales Greens say their state office in Sydney has been damaged by vandals.

Police have been called to investigate the attack in which excrement was smeared on the building and the locks vandalised.

Greens MP David Shoebridge has released a statement saying there are rising levels of vitriol and anger within the public debate in New South Wales.

"This attack is not just an attack on the Greens, it is an attack on the way we conduct our public debate," he said.

"We are building to what will be a hard fought State election campaign in March 2011.

"I am hopeful that this kind of attack will be broadly condemned and we spend the next five months debating principal and policy, not heat and light."

The MP says the attack will not impact on the Greens' work.