BANGKOK, THAILAND - Initial reports into how a Thai train derailed, killing several people and injuring almost 90 near a coastal resort, suggest the driver may have fallen asleep, the state railway said Tuesday.

The overnight passenger train, travelling from southern Trang province to Bangkok, came off the tracks in heavy rain 13 kilometres south of Hua Hin town, a popular tourist getaway and regular retreat of Thailand's king.

Satit Wongnongtaey, the minister attached to the Thai premier's office, said Monday that eight people had been killed but a health ministry statement confirmed Tuesday that the toll was seven, all Thai females.

In total 88 were injured, 22 of whom remained in three local hospitals, the statement said. Acccording to Hua Hin hospital's website, a two-year-old girl was among the dead and six foreigners were hurt.

Montakarn Sivirat, a spokeswoman for the State Railway of Thailand (SRT), said a committee had been set up to investigate the accident and will conclude its inquiry within five days.

"The SRT governor has said that the accident may have been caused by the driver falling asleep," she said.

Transport Minister Sophon Zarum said Monday that the train appeared to have gone through a red light signal and was speeding before the incident, which happened at 4:50am Monday (2150 GMT Sunday).

One passenger also told Thai TV's Channel Three that the train was speeding, saying "it shook before it lost control".

Rail services in the south, which ground to a halt on Monday as a result of the incident, resumed early Tuesday morning, Montakarn told AFP.

"SRT estimates damages from the accident will total 129 million baht (S$5.4 million), " she added.