Erratic NSW driver leaves rider critical

A Sydney man will face court over an alleged hit-and-run accident which has left a motorbike rider fighting for his life in hospital.

It's alleged the 29-year-old was driving erratically along the Pacific Highway near Cowan on Saturday morning when his car collided with a motorbike.

The 40-year-old motorcyclist suffered serious injuries and was taken to Royal North Shore Hospital in a critical condition, police say.

Officers arrested the 29-year-old driver on Sunday and charged him with four offences including negligent driving.

He was refused bail to appear at Gosford Local Court on Tuesday.