Oil has been located in the water south of Townsville, Queensland Transport has confirmed.

A specialist aircraft will leave Cairns early on Saturday to do a complete sweep of the area of Cape Upstart, between Ayr and Bowen and the reef islands to check how far the oil has spread.

Oil pollution teams are now being readied for work on Saturday.

A telephone hook-up early on Saturday morning will co-ordinate the next step of any clean-up, depending on what the early-morning flight finds.