A pilot has died after a helicopter crash in Sydney on Saturday morning.

Emergency services were called to remote bushland off Tuff Hill Lane, South Maroota, north of Windsor, after reports of a helicopter crash shortly before 11.50am.

Crews responded and accessed the site through difficult terrain and flood-affected bushland to find the aircraft on fire.

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Police rescue located the body of a man believed to be aged in his 60s in the wreckage.

He is yet to be formally identified and was the sole occupant of the aircraft.

Sydney news helicopter pilot Andrew Millett spotted the plume of smoke while working on floods near Wisemans Ferry.

"We turned around and I saw just at that moment, a puff of very thick black smoke starting to appear from the bush not too far from where we were – maybe about five kilometres."

Millett went to investigate the smoke that "just didn't look right", but initially thought it could be someone burning rubbish.

"When I saw part of the wreckage, I realised it was a helicopter.

"We were there within a few minutes. I alerted emergency services and gave them the location because it was in quite a bad terrain environment.

"I got as close as I could and was calling out to see if anyone [was there], hoping someone would respond."

A crime scene has been established and will be held under police guard overnight, with a recovery operation and investigations to continue tomorrow.

The Australian Transport Safety Bureau has been notified and will lead the investigation into the circumstances surrounding the accident.