A man has died after a horrific boating accident where two yachts collided in Sydney Harbour.

Emergency services were called to New Beach Rd at Darling Pt, overlooking Sydney Harbour, about 6.30pm on Friday after reports of the collision.

Eastern Suburbs Police and Marine Area Commands found a man believed to be aged in his 50s with a severe chest injury.

He died at the scene and is yet to be formally identified.

NSW Police said both skippers involved would undergo mandatory drug and alcohol testing and the yachts had been seized for mechanical examination.