Man's body found in Wagga Wagga river

A body has been pulled from a NSW river after a man disappeared while swimming on Wednesday.

A man has been stabbed while trying to help a woman who was being attacked in central Melbourne. (AAP) Source: AAP

A swimmer's body has been discovered in a southern NSW river three days after he disappeared.

The body has not yet been formally identified but police believe it is a 42-year-old man who disappeared in the Murrumbidgee River at Wagga Wagga on Wednesday.

The grim discovery comes as emergency services work to revive an elderly man pulled from the water suffering from a medical episode in Sydney's south.

The incident comes on the same day a body, believed to be that of a 14-year-old boy missing since Tuesday, was found at Maroubra beach and a 27-year-old Pakistani National died after being pulled from a waterhole in Sydney's south.

A 46-year-old man also died in a suspected drowning while swimming in a reserve on the north coast of NSW.