An adviser to the former House telecommunications committee has asked the government to probe TOT's reduction of the concession fee for Advanced Info Service (AIS), which he says has cost the country Bt83.5 billion.

Chianchuang Kalayanamitr yesterday submitted the request to Kaewsan Atibhodi, secretary of the state-sponsored Assets Examination Committee (AEC).

TOT granted a 25-year cellular concession to AIS in 1990.

The telecom had to share annual revenues from its prepaid and post-paid mobile-phone services with TOT on an incremental basis, starting at 20 per cent, then moving to 25 per cent and later 30 per cent.

But in 2001, TOT allowed AIS to share only 20 per cent of prepaid revenues throughout the remainder of the concession period.

From 2001-05, AIS had to pay 25 per cent of its prepaid call revenues to TOT, in accordance with the original concession, with the rate rising to 30 per cent from this year to the end of the concession in 2015.

AIS requested the reduction in its revenue-sharing formula with TOT after CAT Telecom allowed its concession holder, Total Access Communication (DTAC), to pay 18 per cent of its total monthly prepaid mobile-phone revenues to CAT, a change from the original Bt200 per prepaid subscriber per month.

AIS and DTAC, the main rivals, have more than 17.5 million and 11 million customers, respectively.

Chianchuang said the reduced income to TOT amounted to Bt83.5 billion through the entire AIS's concession. AIS is a subsidiary of Shin Corp, which was founded by the family of ousted Prime Minister Thaksin Shinawatra.

Chianchuang also questioned the TOT's reasoning for conceding to AIS's demand despite the state agency's ailing financial status.