Amy Lynn Bradley's family fears she is a victim of sex trafficking after cruise disappearance

The resurfacing of a disturbing photo of a woman missing from a cruise since 1998 has sparked fears she has been trafficked for the sex trade.

Amy Lynn Bradley was on a luxury cruise with her family in March 1998 on the Royal Caribbean ship Rhapsody of the Seas, when suddenly she disappeared. That was 27 years ago — she was 23 at the time.

Amy, together with her mother, father and brother, boarded the ship from Puerto Rico. Three days before arriving at the final destination in Curacao, Amy was gone without a trace.

NBC News reported the last sighting was on March 24 when Amy was seen to be sleeping, after previously partying at the ship's on-board club.

“So that evening, Amy was out at the disco with her brother, other passengers, and crew socializing and having a great time,” FBI special agent Erin Sheridan said.

At 5.30am, Amy was seen dozing outside on a chair in their cabin's private balcony. When her father woke up 30 minutes later, he couldn't find her.

“When we discovered Amy missing, we begged the ship's personnel to not put the gangway down, to not allow anyone to leave the ship,” Amy's mother, Iva, told NBC News.

Before continuing its journey, the ship's crew searched the vessel — without any luck. It then traveled to St Martin and St Thomas in the US Virgin Islands before returning to San Juan in Puerto Rico.

Eventually, the case escalated to the FBI.

Initial theories were that Amy fell overboard. Over the years, however, there have been several reported sightings.

According to the Daily Starin January 1999, a US Navy officer reportedly spoke with the missing woman in a brothel in Curacao, and that she said she was “being held against her will and was not allowed to leave”.

However, out of fear he would be reprimanded by the US Navy for going to a brothel, the officer didn't pass this information on to the family until he retired.

Seven years after the disappearance, the family received a haunting tip-off — prompting fears that Amy has been coerced into the sex trade.

One photo, which was first publicly revealed on an episode of Dr. Philwas from a website advertising escorts, the Sun reports.

The chilling image shows a woman posing uncomfortably with few clothes on. The website, according to the Sunstated the woman's name was “Jas”.

Many people believe this is a photo of Amy about the time when she would have first gone missing.

To mark their daughter's upcoming 50th birthday, Amy's parents are offering a huge reward, up to $US25,000 ($40,000), for any information that leads to finding Amy, and information that leads to the arrest of those responsible for her disappearance.

The Petersburg, Virginia native weighed about 54kg at the time she went missing, was 167cm in height, and had short brown hair and green eyes.

She also has distinctive tattoos: a Tasmanian devil spinning a basketball on her shoulder; the sun on her lower back; a Chinese symbol on her right ankle; and a gecko lizard on her navel. She also has a belly button piercing.

“Myself and my parents have had to endure a lot of sadness, but the last thing that I ever said to Amy was 'I love you', before I went to sleep that night. Knowing that that's the last thing I said to her has always been very comforting to me,” said Amy's brother, Brad Bradley, in an FBI video.