Thai police have arrested a Canadian man who allegedly raped a young British backpacker after a karaoke party. 

Aldo Giovanni Ochoa Saenz, 37, from British Columbia, was said to have been drinking with the tourist, 23, and other foreigners at a karaoke bar in Chiang Mai on September 13.

The two then paired off as the group went their separate ways later that night.

But Saenz took her back to his condo where he allegedly took advantage of her while she was intoxicated.

The woman told police she was shocked when she woke up the next morning naked in bed. She later reported the suspected rape at the Mae Ping district station in the popular holiday town in the north of the country.

Police gathered evidence and secured an warrant from the Chiang Mai Provincial Court to arrest Saenz on suspicion of rape.

Footage shows officers raiding Aldo's hotel room at the Pleasant Condominium in downtown Chiang Mai, just hours before he was due to fly to China on September 23.

They seized his phone and reportedly discovered travel details indicating that he was preparing to leave Thailand.

He was handed over to investigators for further legal proceedings.

Police Colonel Yanaphon Phatthanachai, superintendent of the local station, said officers were further questioning the Canadian about the alleged attack.

The officer added: 'The main evidence supporting the arrest warrant is the alleged victim's testimony and the results of her physical examination, which indicated that sexual intercourse had taken place.

'We are preparing charges of rape and sexual assault, as the victim claims she was unable to resist.'

Police Lieutenant Colonel Danai Lamliangphon said Saenz has denied the allegations, claiming the sex was consensual.

The police officer said: 'The suspect told police that he and the British woman went drinking together on September 13. They went to Warm Up and 67 Bar Karaoke as part of a group of seven people.

'The group included people of several nationalities, including people from the Philippines, the UK and the USA.

'The British woman told us that she was drunk and later woke up and realised that she had been sexually assaulted. She also questioned whether the suspect might have put something in her drink because she became intoxicated unusually quickly.

'We questioned the suspect about this allegation, but he denied putting anything in her drink.

'The doctor's test results did not find any drugs. However, the medical examination found traces of semen.

'The suspect also said that he planned to leave Thailand [on] September 23, and travel to China.

'The case is currently awaiting the suspect's detention.'