New South Wales Police have raided a plane that arrived at an airport south of Wollongong two weeks ago from Coffs Harbour, after its last recorded stop in the Philippines more than a month prior.

Officers boarded the plane at the Illawarra Regional Airport in Albion Park on Wednesday, seizing a number of items.

Police would only confirm an operation was underway as part of an active investigation.

It is understood officers and lawyers have been investigating at the airport over the past few days.

A source has told the ABC a man was arrested and drugs are involved but police will not confirm the claims.

The ABC was also told someone had bought the plane and had it flown from overseas to the Illawarra Regional Airport.

The US-registered Swearingen Merlin 3 twin-turbo prop arrived at the airport on the afternoon of June 27.

Flight tracking information shows it came from Coffs Harbour.

But the last flight recorded in the plane's activity log prior to that journey was between Guam and the Philippines on May 5.

There is no log of the flight entering Australia from the Philippines.

An aviation source has told the ABC the plane may have flown to Australia using only visual references.

The source, who asked not to be named, said it would be strange for a plane to fly that distance into Australian airspace using visual flight rules, instead of instrumental flight rules navigating with electronic signals.

The flight activity log, which dates back to early May, shows the plane flew between airports across the USA including Punta Gorda in Florida, Seattle in Washington, Cold Bay in Alaska and via Missouri, Texas, California and Washington state.

It travelled to Hawaii and the Marshall Islands before arriving in Guam.

It is understood that NSW police want to fly the plane to Bankstown Airport to dismantle it and conduct a more thorough search.

Earlier on Wednesday, police attached to the Lake Illawarra Area Command said officers from the Middle Eastern Organised Crime Squad were leading the investigation.

But police have declined to confirm whether the squad is involved.

Workers at the airport recalled the plane arriving on June 27, due to the loud noise of its engines.

They told the ABC it had sat outside a hangar since that time, except for last Friday when it flew-out for several hours then returned.

A local plane watcher who did not want to be named said the plane had been coming and going from the airport since late June.

"It might go away for a day and come back," he said.

"If we don't see it on the Monday, we'll see it on the Wednesday."

The plane is registered to a corporation, Oregonian Aeroclub, in the Delaware city of Wilmington in the USA.

But online searches uncover little to no information about the organisation.