A female Japanese tourist has been found strangled with a USB cord in a hotel in Thailand as police question her boyfriend over the death.

Ami Hosoe, 25, from Gifu prefecture, had checked into the Parc Borough hotel in Chiang Mai with her partner on July 29.

The pair had arrived in Bangkok for business on June 24, and extended their stay to take a vacation in the mountainous northern province.

They were seen shopping at a convenience store at around 3:45 am on July 31, hours before they were due to check out at noon. They went back to the hotel to sleep, but the woman's partner said he woke up when he noticed his partner had left their bed.

He claimed he walked over to the bathroom, but was horrified to find Ami's corpse with a white USB cable wrapped around her neck in their bathtub on Monday morning.

Muang Chiang Mai District police officers arrived at the scene, where they found the man 'distraught and in a state of panic'.

They said Ami was lying face down in the bathtub wearing a black tank top and black underwear, with her body indicating she had been dead for a few hours.

Hotel porter Chainat Namcharoen, 51, said he was told by housekeeping staff about the dead tourist and rushed over to check on the room before informing managers about the incident.

The Japanese tourist claimed that his partner had been suffering depression and panic attacks, and had previously tried to strangle herself with a hairdryer cord on Sunday evening, but he was able to save her. He told police he then hid away the dryer out of fear of a repeat incident.

Police Major General Thawatchai Pongwiwattanachai, the commander of Chiang Mai Provincial Police, arrived at 11:50 am to question the tourist and gather evidence at the hotel.

The policeman said: 'The dead woman's boyfriend has denied having any arguments with Ami during their trip. He claims that she killed herself. There are no other suspects, as cameras at the hotel did not show anybody entering the room.

'We have interrogated the boyfriend and may question him again once we have more details about the deceased's medical history and her cause of death.'

CCTV footage also found that the couple were the only ones to have entered their hotel room.

Police have already contacted the Japanese Consulate to inform them of the case. They are now waiting for the results of the post-mortem examination at the Maharaj Nakorn Chiang Mai Hospital and are trying to obtain Ami's medical history regarding her mental health.