Police in Tokyo have detained two American men as part of an investigation into the death of a female Irish foreign exchange student.

Nicola Furlong, 21, was found unconscious in a Tokyo hotel room early Thursday morning and was later confirmed dead at a nearby hospital, Kyodo reported.

An autopsy showed that Furlong might have been strangled.

The man who was in the room with Furlong when hotel staff found her was described as a 19-year-old American who identified himself as a musician. He and a 21-year-old man, who was found in the hotel room of Furlong's female friend, were arrested Saturday, according to Japanese and Irish news reports.

The two men were charged with indecent assault on Furlong's friend, but police also suspect they were involved in Furlong's death, sources told Kyodo.

The Irish Independent described Furlong as a Dublin City University student who was studying abroad for a year.

She was attending school at a university in Takasaki, about 60 miles (95km) northwest of Tokyo, Kyodo said, citing police sources.

Furlong and her friend were reportedly in Tokyo to see a Nicki Minaj concert.

After a guest complained about a loud noise coming from a hotel room around 3:00am Thursday, a hotel employee found the Irish woman lying unconscious on the floor with the man standing nearby, sources told Kyodo.