A probe has been launched into the mysterious death of an Australian Instagram influencer, whose body was found aboard a Mexican billionaire’s luxury yacht in Greece over the weekend.

Sinead McNamara, 20, had been working on the £108-million Mayan Queen IV superyacht for four months when she was discovered on Friday.

The 92-metre yacht owned by Alberto Baillères, an 87-year-old mining magnate, has been ordered by the Hellenic Coast Guard to remain docked at the port of Argostoli, on the Ionian island of Kefalonia, while detectives interview crew members and forensic tests are carried out.

An autopsy has been ordered to determine the cause of Ms McNamara’s death.

Originally from Port Macquarie in New South Wales, Ms McNamara was a Sydney-based social media influencer who had been working on the vessel as it sailed around Europe over the summer.

It is unclear what type of work Ms McNamara was doing on the yacht. She had been promoting swimwear, underwear and skincare brands to her 14,000 Instagram followers over the last year while travelling to some of the world's most exclusive resorts.