Pol Col Dusadee Arayawuthi, deputy permanent secretary for justice, told the senate subcommittee probing corruption in transport that 10,000 high-end automobiles, mostly from Britain, had been brought into Thailand every year since 2008.
The combined tax loss was around 60 billion baht, given that each vehicle is supposed to be taxed at one million baht or more, he added.
Pol Col Dusadee spearheaded efforts to tackle the evasion of tax on imported luxury cars when he was secretary-general of the Public Sector Anti-Corruption Commission (PACC). He was transferred to the Justice Ministry earlier this month amid criticism that the government wanted to prevent him unveiling corruption in government agencies, including the car case and flood prevention projects.
The government claimed that Pol Col Dusadee was simply promoted to a higher position.
When he was the PACC chief, the agency found about 10,000 invoices of luxury cars imported from Britain were falsified. The prices declared were far below the actual value of the vehicles, an attempt to avoid paying full import taxes.
It suspected that both politicians and Customs Department officials were involved in the scam.
On Tuesday at parliament he voiced his frustration, saying that 108 officials involved in the scam were left untouched.
"They might be backed by either politicians or senior ministry officials, otherwise they could not stay,'' he told the panel.
The case is in the hands of the National Anti-Corruption Commission (NACC). And Pol Col Dusadee on Tuesday offered to sit in an NACC subcommittee to help take action on those involving in the scandal.
He also proposed the Senate to come up with a set of measures to prevent tariff evasion on exported cars.
Pol Col Dusadee recommended that the customs officials calculate the tariffs based on the real values of the cars, determined either from the exporters' documents or cross referenced with authorised dealers. Also the import firms' transactions must be verified to aid revenue collection, he added.
Early this year, four companies importing luxury cars called on the ministry to look into reports that Thai overseas students were abusing their right to bring cars into Thailand without having to pay fees and 200% taxes like proper importers have to.