Flight QF24 from Bangkok to Sydney was forced to land in Cairns about 5.45am on Sunday after the 34-year-old man became unruly.

About seven Australian Federal Police officers escorted the passenger from the plane, according to a Fairfax Media journalist on board.

Passengers were told the man had tried to steal bottles of Scotch whisky from the cabin crew area.

It is understood the man was detained on board by two plainclothes AFP officers and moved from economy class towards business class.

He shouted on and off for several hours, at one point yelling "turn off the f---ing light c---", the Fairfax Media journalist said.

An AFP spokesperson said officers had "removed the passenger without incident".

He was charged with behaving in an offensive and disorderly manner and interfering with the crew of an aircraft.

The second offence attracts a $5000 fine, two years' jail or both.

A Qantas spokeswoman said she was unable to answer specific questions because the man was under investigation. But the airline confirmed in a statement the flight diversion was "due to an intoxicated passenger".

The flight, which had been due to land in Sydney at 6.45am, arrived just after 9am.

Some passengers were due to fly from Sydney back to Cairns.

But they were reportedly not allowed off the plane when they landed in Cairns and then missed their connecting flights due to the diversion.

The man is expected to appear before the Cairns Magistrates Court on Monday.