Traffic is queued for eight kilometres after a fatal motorbike crash on the M5 in Sydney's south-west on Monday afternoon.

Emergency services were called to the motorway about 3.30pm after receiving reports of a multi-vehicle crash.

One man, who had been riding a motorbike, died at the scene.

In a statement, police said the crash unfolded near the intersection of Heathcote Road at Hammondville, near Moorebank.