Suspected child abduction in Sydney

A police search is underway after a suspected child abduction in Sydney's southwest.

Police say they hold concerns for a child and a man who were last seen on Brown Road and Kinghorne Road, Bonnyrigg Heights at 4.45pm on Tuesday.

The child is described as having blond hair and wearing shorts and joggers.

The man is described as a Caucasian and wearing a khaki cap, a green top and pants.

Later, police said an extensive search of bushland and nearby residences was completed however the pair haven't been located.