Paramedics tend to the man who was caught in an excavator.

Paramedics tend to the man who was caught in an excavator.

A man had his leg torn off after he became caught under an excavator in Sydney's south.

The 30-year-old was at a construction site on Marsh Street, Wolli Creek when the accident happened on Tuesday morning.

He was treated by Careflight paramedics before being taken by ambulance to St George Hospital in a serious but stable condition.

Careflight said the man's leg was torn off and blood transfusions were administered at the scene.

A WorkCover investigation is underway.

AAP