A teenager has been rushed to hospital after a near-drowning at the Georges River in Sydney's south.

Emergency services were called to the river at Keith Longhurst reserve in Kentlyn just before 1pm, following reports a man in his late teens was pulled unconscious from the river.

Six ambulance crews and one helicopter were sent to the scene, but an ambulance spokesman said access was difficult.

It's understood the scene was a 1.5 kilometre walk from the nearest road, and phone reception was poor.

The teen was conscious and breathing, an ambulance spokesman said, and was winched out by the rescue helicopter.

He was airlifted to Liverpool Hospital in a stable condition.

More to come