Thai police said today that traces of cyanide were found in the cups of six tourists who were poisoned at a hotel in Bangkok.

The four Vietnamese and two American nationals were found dead inside a luxury room at the Grand Hyatt Erawan in Bangkok shortly before 5:30pm local time on Tuesday July 16.

Lieutenant General Trairong Piwpan, chief of the Thai police force's forensic division, said there were traces of cyanide in the cups and thermoses that police found in the room, but initial results from post mortem examinations are expected Thursday.

Bangkok police chief Lt. Gen. Thiti Sangsawang identified the dead as two Vietnamese Americans and four Vietnamese nationals, and said there were three men and three women.

Five of the dead were named by police as females Sherine Chong, Thi Nguyen Phuong and Thi Nguyen Phuong Lan. Two dead men were Dinh Tran Phu and Hung Dang Van. The sixth has not been named.

Five bodies are believed to have been inside the room and one outside the door. Police are searching for a seventh member of the group, who they suspect was involved.

Police Lieutenant General Thiti Saengsang, commander of the Metropolitan Police Bureau, along with Major General Noppasin Poolsawat, deputy commander of the Metropolitan Police Bureau, were dispatched to the suspected crime scene.

Police Lieutenant General Thiti Saengsang said: 'Hotel staff found the dead inside the room. They called the police immediately and forensic officers arrived.

'This was not self harm, but someone caused the deaths. We are tracing every step since they got off the plane.

Thai prime minister Srettha Thavisin and other government ministers were scrambled to the hotel late on Tuesday to desperately try and protect the country's lucrative tourism industry. They assured people that it was an isolated case and ordered a swift investigation.

VIDEO SUBTITLES

0.24 - 0.35 : We received an order from the commissioner of the Metropolitan Police Bureau to provide an update at 11 AM

0.35 - 0.47 Commander Watee, commander Phusatan, joined hands with Immigration Bureau, represented by the deputy commissioner, with commander Theeradech

0.47 - 0.57 The first person is a woman in a white shirt. We found that she is 46 years old and arrived in Thailand,,,

0.57 - 1.07 ,..at 12.28 PM and had entered Thailand 11 times. On July 12, he checked into room 1219 and stayed there on July 13. On July 14...

1.08 - 1.18 To prevent misunderstanding and confusion, I would like to provide a timeline of each event…

1.19 - 1.30 Two are Vietnamese but actually have American nationality, One is aged 55 years. This victim wore a navy blue shirt and was lying beside Woman No. 1.

1.31 - 1.37 He entered Thailand on July 7 at 9.55 AM

1.38 - 1.51 We have not performed a quantitative analysis. The qualitative analysis revealed cyanide in the liquid inside a teapot and stains on the cups

1.51 - 1.57 As reported by Deputy Commissioner Police Major General Noppasil, and the findings of the forensic division that Commander Trairong has already reported

1.57 - 2.13 As for matters related to foreign affairs, such as Vietnam, the Immigration Bureau has appointed a unit to coordinate with the Ministry of Public Security, which will receive information for further investigation on their related aspects

2.25 - 2.35 Cases like the one in Bangrak or this case are personal matters and are not related to criminal organisations operating in Thailand