Police have arrested the driver of a 50-tonne truck after a chase of almost 70 kilometres in northern New South Wales.

Police were called just after 8:00pm on Saturday after receiving multiple reports of a B-double being driven erratically without headlights, around 20 kilometres south of Grafton.

Officers allege that during the pursuit, the 48-year-old driver tried to run a patrol vehicle off the road and later side-swiped a parked police truck that was blocking motorists from entering Grafton as a precaution.

No one was injured in either incident.

The pursuit continued 50 kilometres north until the driver stopped at Chatsworth Island, where police allege he resisted attempts to remove him from the cabin.

The driver was taken to Grafton Base Hospital for mandatory testing and was kept in hospital for observation due to concerns for his health.

Police suspect the driver, from Nerang in Queensland, was under the influence of drugs.