Image copyright KARE-TV Image caption An itinerary found the sisters had been touring Africa since 1 September

Two US sisters discovered dead while on holiday in the Seychelles died of excess fluid in their lungs, according to police on the Indian Ocean resort.

The bodies of Annie Marie Korkki, 37, and 42-year-old Robin Marie Korkki were found by hotel staff last week in their luxury villa at the tropical resort.

Post-mortem examinations have determined the Minnesota natives died from "acute pulmonary edema".

Cerebral edema, or fluid on the brain, was also cited in Anne Korkki's death.

Image copyright Facebook Image caption The women's brother said his sisters were adventure-seekers who lived life to the fullest

The police report said no "no visible signs of injuries" were found, adding that the investigation continues and toxicology tests are pending.

The sisters were discovered on 22 September by a hotel employee who tried to wake them at the $2,000-a-night Maia resort on Mahe, the Seychelles' main island, the hotel said.

Dr Patrick Lank, a Northwestern Medicine assistant professor of emergency medicine in Chicago, said edemas are commonly seen in drug overdoses.

But fluid on the lungs can also be caused by viral infections or by living at altitude, though the Seychelles is not situated at elevation.

"Two people at the same time is odd," Dr Lank told Associated Press. "It suggests more of a toxicologic or environmental cause, or a potential infection if they're travelling together."

Image copyright Facebook Image caption The sisters were staying at the $2,000-a-night Maia resort on Mahe

Both sisters worked in banking. The LinkedIn account of Robin Korkki, who lived in Chicago, Illinois, lists her as a commodities trader.

Her younger sister, who was based in Denver, Colorado, worked at JPMorgan Chase, according to her Facebook page.

The day before their bodies were discovered, the pair had been drinking at the resort and had to be helped to their rooms by staff at 20:15, according to local media.

The women's brother, Chris Korkki, of Lakeville, Minnesota, told CBS station WCCO-TV his sisters were outgoing, generous, kind and "lived life to the fullest".

An itinerary found at the hotel indicated the sisters had been touring Africa since 1 September.

Before arriving in Seychelles on 16 September they had toured Kenya, Tanzania and Zanzibar.