A young boy who was bitten by a shark in Sydney Harbour last week has died in hospital.

Twelve-year-old Nico Antic had been jumping off a rock ledge with friends on 18 January when he was attacked by what authorities suspected was a bull shark.

We are heartbroken to share that our son, Nico has passed away, his parents Lorena and Juan said in a statement.

The incident was one of four reported shark attacks along the New South Wales coast over two days.

Nico was described by his family as a happy and sporty young boy with a generous spirit. His friends showed remarkable bravery by jumping into the water to assist him following the attack.

Despite being hospitalized and placed in an induced coma after surgery, Nico could not recover from the serious leg injuries he sustained.

In light of the recent spate of shark attacks, beaches in Sydney were closed to protect the public as marine experts noted that environmental conditions conducive to shark presence may have been exacerbated by recent weather patterns.

The series of attacks have included incidents involving a surfer escaping without injury and another man suffering life-changing injuries. Authorities are emphasizing the need for caution and awareness in shark-prone waters.