A man has died following a truck crash in Werribee South this morning.

Police and emergency services were called to the Princess Freeway following reports a semi-trailer had struck a barrier and rolled around 3.20am.

The male driver, who is yet to be formally identified, died at the scene.

The Geelong-bound lanes of the freeway are currently closed between Sneydes Road and Duncans Road.

Police will investigate the cause of the collision.