Police launched a murder probe after the body of a mystery woman was found stuffed inside a suitcase in Thailand.

Cops fished out the suspicious luggage when it was spotted floating in the vast Mekong River around 20 metres away from Nakhon Phanom provincial Marine Police Station on September 28.

The black 90cm by 60cm case contained a plastic bag that was used to wrap around the decomposing woman's body along with heavy rock that was supposed to keep it from floating.

Upon inspection, a fair-skinned corpse about 5'3'' in height and estimated to be 40 years old was revealed inside. She had been wearing a blue tank top and blue jeans, while a pair of eyeglasses and a white jacket were in the bag with her.

Authorities searched for the woman's identity and took her body to Srinagarind Hospital in Khon Kaen province for an autopsy.

Police Lieutenant Colonel Prasoetsak Nuanbat said: ‘Our patrol inspectors were informed by the royal Thai navy that they found a woman stuffed inside a suitcase floating along the Mekong. We have alerted the rescuers and related authorities to cooperate with the investigation.'

Local fishermen informed officers that they had seen the luggage floating along the body of water three days since the woman was discovered, but they ignored the object thinking it was only trash.

Further inspection revealed the dead woman had a wound on her face after being hit with a hard object. No other apparent injuries were found in her body, but investigators ordered a detailed autopsy report. Officers believe she had been dead for around five days when she was found.

Thai authorities are also coordinating with officers from neighbouring countries as the luggage may have floated and crossed the border along the Mekong that flows through six countries China, Myanmar, Thailand, Laos, Cambodia, and Vietnam.