A half-naked dead woman was found stuffed in a chained and padlocked suitcase floating in a reservoir in Thailand.

The suspicious luggage was discovered by rowing athletes who were training at the Khlong Bang Phai Reservoir in Chonburi, early morning on Wednesday.

Police arrived at the scene at 6:30 am local time and found the black King Safari-brand suitcase secured with chains, cable ties, and a padlock. They cut through the metal and found the decaying corpse of a woman inside.

She was topless, had bruising on her neck, chest and face, and was estimated to have been dead for five days. Forensic officers believe she is aged around 30 years old.

Nine barbell plates totalling 16 kilos (35 pounds) were also crammed in the front compartment of the suitcase to weight it down.

Police Lieutenant Mintrathit Thongsai, deputy investigation chief at the Huai Yai district station, said: 'We could not examine the wounds on the body, so it must be sent to the Institute of Forensic Medicine for a thorough examination to determine the cause of death.

‘We speculate she was murdered and the body was stuffed into the suitcase, weighed down, and dumped into the water to conceal the crime.'

Lieutenant Kasemsin Boriboonwasin, a national team rowing athlete, said he was in the middle of practice when he noticed the suitcase drifting some 80 to 90 metres (around 260 to 295 feet) from the shore.

When he paddled closer to inspect, he saw blood and fluids leaking out, and smelled an overwhelming foul stench. He dragged the luggage onto land before calling the police.

He said: 'We were practising until 7 pm yesterday but the suitcase wasn't there. We only found it the next morning.'

Authorities said the reservoir is under the jurisdiction of Thailand's navy, and is being used as a training ground for rowing athletes.

The area is surrounded by forests with no CCTV. Investigators said heavy rains in the past few days may have washed away evidence.

Private Phakkathorn Phanchaem, 22, a guard at the reservoir, said the reservoir is restricted though illegal fishermen sometimes visit.

He claimed to have seen lights and heard dogs howling in the area in the nights leading up to the grisly discovery.

Police said they were investigating if the case is linked to a previous suspected murder, where a woman was also stuffed into a suitcase and submerged using weights in Rayong, just 14 kilometres (8.6 miles) away.