Immigration Bureau chief Pharnu Kerdlarpphon identified Fa Jun He, Shao Hua Ye and Zhen Zu Wu, all Chinese nationals, as the main suspects in the theft of the Montblanc watch from a shop in Gaysorn Plaza on Tuesday.
They were believed to have caught a flight to Shenzhen on Shenzhen Airlines that left Bangkok at 7.30pm on Tuesday, he said.
The three arrived at Suvarnabhumi airport in the early hours of Tuesday and fled the country after the theft, Pol Lt Gen Pharnu added.
They fled the shopping centre in a taxi and one of them was dropped off in front of the Thai Red Cross Society on Henry Dunant Road before joining the other two at the airport, he said.
His information conflicted another investigation undertaken by the Metropolitan Police Bureau (MPB).
MPB chief Pol Lt Gen Kamronwit Thoopkrachang and Thitirat Nongharnpitak, the lead investigator, did not conclude that all three had already left Thailand as they could probably go to other destinations in the country.
The two officers said more evidence was need before police can seek an arrest warrant from the Criminal Court.
It was possibloe they were not Chinese but tried to speak the Chinese language to fool witnesses and investigators, Pol Maj Gen Thitirat said.
Police on Wednesday questioned the taxi driver.
Driver Peerapol Iam-saard picked up the three men about Tuesday at 3.30pm, just half an hour after they had allegedly stolen the wristwatch from the store.
Police said on Wednesday the taxi driver and the shop owner were not suspected of being involved in the theft.
The stolen watch is one of only eight, a limited edition by Montblanc, and the only one in Thailand.