The Expressway Authority of Thailand (Exat) warned motorists on Friday that legal action will be taken if they fail to pay toll charges.
Exat said the agency will press ahead with legal charges against drivers who refrain from paying tolls within the given deadline.
Expressway users who intentionally or unintentionally do not pay tolls by driving through manned toll gates will receive a letter based on the address attached to their car's registration plates. Car owners could be fined up to 10 times the toll fee if they fail to pay the charges.
Drivers have seven days to pay the fare before Exat sends them a written warning, this time with extra charges.
"If violators still do not pay the fines or deny the charge within the deadline, Exat will proceed with legal action," the agency said.
Exat did not detail the number of motorists who have not paid the toll fees, only saying 28 court cases had been finalised, while 27 others were still in the process of having court cases finalised.
More than 1.5 million vehicles use the tollways operated by Exat daily, according to the company's website.
