Sydney girl, 13, missing nearly a week

Greta Stonehouse

A 13-year-old girl missing from Sydney's northern beaches for nearly a week may have left the city to meet up with her estranged father, police say.

Emily-Rose King was last spotted leaving a St Leonards medical facility in the city's north last Thursday, with her family concerned for her welfare after recent treatment for an infection.

"We have information that she may be possibly headed towards Queensland or Newcastle addresses, possibly to meet up with her estranged father," Acting Inspector Simon Whitfield told 2GB on Wednesday.

Emily was last seen wearing a black 'Lacoste' jacket, black tracksuit pants with three white stripes, and white 'Nike' sneakers.

Police have released an image of the girl and urged anyone with information to come forward.