A motorcycle rider has died following a horror crash with a truck driver on a busy Sydney motorway.

A NSW Ambulance spokeswoman told Daily Mail Australia the motorcyclist died at the scene and the truck driver is being assessed.

The fiery accident happened before 3.30pm westbound on the M5 motorway at Moorebank, causing traffic chaos across the city ahead of the peak-hour Monday evening commute with closed westbound lanes.

The fiery accident happened before 3.30pm westbound on the M5 motorway at Moorebank

NSW Ambulance said a second crash happened minutes later at 3.35pm on the M5 motorway in the opposite direction.

Another motorcycle rider collided with a car on the eastbound lanes.

Two patients are being treated at the scene with reports of a broken collarbone, before being transported to hospital.

Traffic is being diverted onto Henry Lawson Drive as cars are backed up for kilometres.

The two accident is believed to have occurred at Heathcote road just after 3pm.

The incident caused traffic chaos across the city ahead of the peak-hour Monday evening commute with closed westbound lanes