MOTORISTS travelling on Kennedy Drv face ongoing delays with roadworks to continue after the discovery of unstable soil forced an extension.

The roadworks, between the bridge over Cobaki Creek and Limosa Rd in Tweed Heads West, were due to be completed by Monday but the finish date has been pushed back after contractors uncovered unstable marine clay while excavating.

Tweed Shire Council said the roadworks, and the associated traffic delays will continue until at least the end of the week with delays from 7am to 6pm daily.

Motorists are urged to avoid the area if possible between those times.

"There's no easy solution to easing the pain for motorists, except to urge them to use the alternate route via Bilambil and Terranora roads if they cannot travel early and clear the roadworks before 7am,” construction engineer Bob Hanby said.

"And again, at the end of the day if their commute puts them on Kennedy before 6pm we advise them to go the alternate route.”

Council is confident that the project will be completed by the end of the week but warned if more of the unstable clay is uncovered, the project end date would be pushed out even further.

The roadworks are part of the final stage of a $9 million upgrade to Kennedy Drv from the bridge to the Pacific Motorway.