Cruise giant Royal Caribbean International issued mass refunds after dozens of Australian families complained their relaxing cruise was ruined soon after the ship left Sydney this September.

Passengers aboard the 138,000-gt Voyager of the Seas (built 1999) were forced inside their rooms as nearly 1,300 workers from Indian tobacco company Kamla Pasand overran the vessel, according to Australian news reports.

The employees attending Kamla Pasand's company conference aboard Voyager of the Seas took over the pool decks and bars, throwing wild parties with skimpily clad burlesque dancers, some in Playboy Bunny suits.

Other passengers were blocked from accessing many parts of the ships, and some female passengers complained they were filmed on cameraphones by the rowdy men on board.

Kamla Pasand's men accounted for more than a third of the ship’s capacity of 3,000 passengers, Nine Network's A Current Affair reported, making the coveted main buffet off-limits to many guests, who were then directed into other restaurants by stressed Royal Caribbean staff.

They also brought "crates and crates" of their own food onto the ship, a passenger told local journalists.

An investigation is under way, Royal Caribbean said in a statement to A Current Affair.