Six foreign nationals were found dead in a luxury hotel room in central Bangkok on Tuesday, Thailand's Prime Minister Srettha Thavisin said, with police suspecting they were poisoned.

"There were no signs of a struggle," Srettha told a press conference at the Grand Hyatt Erawan hotel in the upscale Pathum Wan district, where the incident took place.

"We need to conduct an autopsy to see if they had ingested anything," he said, dispelling rumors the deaths were connected to a theft and had involved a shooting.