Motorists in the Thames-Coromandel area should exercise extreme caution if travelling on State Highway 25 between Thames and Tairua.

Emergency services were alerted to an oil spill in the area around 1.40pm today.

"The spill is described as being from the top of Kopu-Hikuaia Road (SH25A) to at least Tairua," says police spokesperson.

"Contractors are currently dealing with the spill but motorists are advised to take extreme care in the area."