The Westpac Lifesafer 23 rescue helicopter was sent at 3.40pm after a member of the public rang Triple 0 to report smoke on the horizon.

A police spokesman said officers were contacted at 2.51pm and went to the scene.

They alerted the helicopter crew which began a search of the area.

CEO Stephen Leahy said the crew located a large Maltese container ship that had left Botany Bay early on Wednesday, June 26, bound for Melbourne and was about 10 nautical miles due east of Tuross Head.

"We believe the smoke was the container venting its exhaust systems, releasing dark smoke into the air," Mr Leahy said.

"There is no distress call or emergency beacons activated, no sign of debris or oil slicks.

"We will search for a bit longer to confirm there are no other vessels."

He said the crew was checking each small boat in the area to ensure none were in danger.

At about 4.20pm the container vessel CMA CGM New Jersey was heading south off the coast of Narooma, according to Vesselfinder.com.

A Marine Rescue spokesperson said Batemans Bay and Narooma crews were activated but were then stood down.

Marine Rescue tried to contact the informant, but they did not respond.

However, he said the informant had done the right thing by calling emergency services.

"We always encourage anyone who sees anything like that on the water to report that because, you never know," he said.

Flightradar tracks aircraft movements.