By Andrea Lorenz

HOUSTON, Jan 31 (Reuters) - Several ill passengers who disembarked from a Princess Cruises ship in Houston on Friday said they felt like prisoners forced to their cabins for days when the vessel suffered the second outbreak of a stomach illness to hit a cruise ship in a week.

The seven-day cruise returned a day early on reports of fog in Houston at around the time of its planned arrival, the company said.

"They threatened people, told them that if they didn't stay in their room, they would have them put on a ... Coast Guard ship and brought back to land. It was terrible," passenger Steve Juneau told local ABC broadcaster KTRK.

Julie Benson, a spokeswoman for the cruise line, said it is policy to ask passengers suffering from stomach and digestive problems to stay in their rooms to prevent problems from becoming worse. Those in cabins are provided with room service.

"The last thing that we want to do is to have passengers out and about with those types of symptoms and spreading the illness to others," she told Reuters. Some passengers felt a few crew members may have overstepped their bounds by confining those who were not showing any symptoms to their rooms.

During the course of the cruise, 178 passengers and 11 crew members reported ill to the ship's medical center, the cruise line said.

The ship had 3,104 passengers and 1,149 crew members on board. About three passengers have symptoms of the gastrointestinal norovirus, the cruise line, which is owned by Carnival Corp, said Benson.

Some passengers said they were treated kindly by the crew, but many were skeptical of the reason for the early return.

"I wanted to get out," passenger Robert Fisher told KTRK. "I was tired of being held as a prisoner in the room."

Passenger Cathy Russell told local NBC broadcaster KPRC she was quarantined to her room for 80 hours and treated well.

"They brought us whatever we needed ... provided room service, so they did what they could do," Russell said.

In response to the outbreak, the crew "immediately implemented aggressive and comprehensive disinfection measures developed in conjunction with the U.S. Centers for Disease Control and Prevention (CDC)," the company said.

The ship was being sanitized before its next scheduled departure on Saturday.

CDC officials met passengers as they left, asking them questions to help find out what might have been behind the outbreak. The CDC also took specimens for analysis.

The ship's return comes after a Royal Caribbean ship cut short a Caribbean cruise when more than 600 people came down with a gastrointestinal illness..

The Royal Caribbean cruise line said it believes the illnesses are consistent with norovirus, a highly contagious virus spread from an infected person, contaminated food or water, or by touching contaminated surfaces, according to CDC.