A cruise worker on board an Italian ship 'murdered her newborn son' as horrified co-workers raised the alarm as the vessel sailed off the coast of Argentario, Tuscany.

The Filipino, 28, was a member of the cabin crew on board the cruise ship and according to her colleagues, she had kept her pregnancy hidden.

In a horror set of events, the woman had allegedly been in a cabin when other staff heard piercing cries coming from the room.

They realised something was wrong when the wails stopped and didn't pick back up.

Fearing the worst, the panicked crew members immediately called the police.

A cruise ship worker, 28, 'murdered her newborn son on board the vessel' in Tuscany before police found the infant's body in a cabin she shared with other ship staff. Pictured: Argentario, Tuscany

Police scrambled to the ship in a patrol boat and officers searched through the cabin and other rooms within the ship as they carried out photographic surveys.

The newborn's body was discovered in the cabin that the mother shared with other crew personnel. 

After finding the new mother, who was reportedly in a confused state, she was taken to the emergency room in Grosseto, Tuscany.

On Monday morning, the Grosseto prosecutor's office arrested the woman who is accused of voluntary homicide.

The unnamed woman gave birth to the little boy about two days before allegedly killing him, police said. 

The child's body is in the morgue and an autopsy is set to be arranged.

The autopsy will also establish whether the woman was in her final month of pregnancy or whether the newborn was premature.

According to an initial external examination, the death of the infant was not caused by suffocation or strangulation, but is thought to have been left alone inside the three-by-two metre cabin for hours with no milk or medical care.

Cops spoke to several crew members following the tragic incident - and they all revealed they had no idea the woman was pregnant.

Colleagues explained that their stomachs would not be visible on sailing days under uniform and they hadn't witnessed her suffering with any illnesses or sickness related to pregnancy in public. 

Police are also believed to have verified the witness statements with photos of the team members on their mobile phones - to see whether the woman appeared pregnant in any images.

After the authorities had carried out their checks on board the ship, the vessel resumed its scheduled navigation.

The motive behind the tragic murder is not yet currently known, but police are continuing their investigations into the case.