Drivers battling 5km queues on M1 Motorway after two separate incidents at Mooney Mooney and Cowan

A truck breakdown and a two-car crash have caused havoc for commuters on the M1 motorway this morning, with traffic backed up for at least 5km.

Drivers are being warned to brace for delays this morning.

Southbound lanes on the M1 Motorway were closed but have since reopened after a truck broke down near the Pacific Highway south of the Hawkesbury River Bridge at Cowan.

A tow truck was on site around 6.30am to move the vehicle.

A two-car crash between Jolls Bridge and Hawkesbury River Bridge at Mooney Mooney on the M1 also temporarily closed lanes and added to the traffic delays.

This is a breaking news story. More information will be added as it comes to hand.