Authorities found five pickup trucks carrying nearly 100 Rohingya before dawn yesterday in the Hua Sai district of Nakhon Si Thammarat province on the Gulf of Thailand.
"There were total 98 Rohingya. Of them, one woman aged around 20 years old died from suffocation while travelling," provincial police commander Kiattipong Khawsamang told AFP.
"The truck was crowded and she also had not eaten," Kiattipong said, adding the group was travelling from Phang Nga province on the western seaboard.
Thai authorities will now process the group to establish whether they were being trafficked by smugglers through Thailand.
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Authorities have in recent weeks discovered scores of other migrants who fled dire conditions in Myanmar, taking advantage of the slightly calmer winter waters in the Andaman Sea to head south.
On January 5 police detained 53 migrants from Myanmar -- the majority of them Rohingya -- in Phang Nga province, a hub for boatpeople being transported on to mainly Muslim Malaysia.
Thousands of Rohingya have fled deadly communal unrest in Myanmar's Rakhine state since 2012.
Rights groups say the stateless migrants often fall into the hands of people-traffickers.
They have also criticised Thailand in the past for pushing boatloads of Rohingya entering Thai waters back out to sea and for holding migrants in overcrowded facilities.
Thailand said last year it was investigating allegations that some army officials in the kingdom were involved in the trafficking of Rohingya.
In June the United States dumped Thailand to the bottom of its list, or to "Tier 3", of countries accused of failing to tackle modern-day slavery.
The ruling junta says it has since taken significant steps to combat trafficking and the exploitation of migrants.