NSW counter-terrorism police have discovered a machine gun and other weapons inside the toilet of an abandoned Sydney house.

Police seized the weapons, including a sniper rifle and pistol, from the unoccupied home in Homer Street, Earlwood on Friday.

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The machine gun, which is capable of firing up to 550 bullets a minute, was hidden with ammunition inside green plastic garbage bags inside a toilet.

Police are yet to identify the owner.

“We would like to know more about who owned these firearms and where they came from,” Superintendent Darren Bennett said.

“The Schmeisser sub-machine gun in particular is a concern.”

The firearms have been sent for ballistic investigation.