BANGKOK (AFP) - A Rohingya woman has died after suffocating in a truck packed with migrants from the Myanmar Muslim minority group as they travelled through southern Thailand, the police said on Monday.

The authorities found five pickup trucks carrying nearly 100 Rohingya before dawn on Sunday 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. Two of the pickup drivers have been arrested on suspicion of people-trafficking, he added.

The Thai authorities will now process the group to establish whether they were being trafficked by smugglers through Thailand.

The 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 Jan 5, the 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.

Myanmar views its population of roughly 800,000 Rohingya - described by the United Nations as one of the world's most persecuted minorities - as illegal Bangladeshi immigrants and denies them citizenship.

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.

Tens of thousands of the world's trafficking victims end up in Thailand as migrants from neighbouring countries "who are forced, coerced, or defrauded into labour or exploited in the sex trade", the US report found, singling out the Thai fishing industry as an area where abuses are particularly common.

The ruling junta says it has since taken significant steps to combat trafficking and the exploitation of migrants.