A Sydney man has been stabbed after answering his door.

A man has been stabbed in the buttocks after answering the door of his south Sydney home.

Police have been told the 48-year-old was stabbed when he answered the door of his Rawson Street home in Rockdale about 6pm on Sunday.

The man was taken to St George Hospital for treatment and a crime scene has been set up.

Police are unable to confirm how the injury came about or whether the injured man and his alleged attacker are known to each other.

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