The Department of Special Investigation (DSI) and a probe committee led by the House secretary-general have found no irregularities in last month's 3G auction.
Tarit: Will present findings to NBTC
The auction did not involve any price collusion, said Tarit Pengdith, the DSI's director-general.
The National Broadcasting and Telecommunications Commission (NBTC) will be informed of the DSI's findings, and a press conference on the matter will be held next week, Mr Tarit said.
The DSI launched the investigation into the Oct 16 auction after receiving a request to do so from NBTC secretary-general Thakorn Tantasit.
Suvichak Nakwatcharachai, the secretary-general of the House who led the probe, said none of the bidders manipulated the auction and all of them complied completely with the auction terms set by the NBTC.
The auction sold licences for 3G mobile phone services on the 2.1 gigahertz spectrum. Advanced Info Service (AIS), Total Access Communication (Dtac) and True Move were the successful bidders. They were also the only contestants.
The probe will officially conclude today before informing the NBTC of its findings.
Mr Suvichak said his committee did not consider whether the NBTC's auction terms were conducive to creating competition among bidders.
The probe's mandate was restricted to examining the behaviour of the bidders, he said.
He insisted that the credibility of his probe committee remained intact, despite Supa Piyajitti, deputy permanent secretary of the Finance Ministry, and Somkiat Tangkitvanich, president of the Thailand Development Research Institute, refusing to recognise it or provide testimony.
Earlier this month, the Office of the Ombudsman asked the Administrative Court to suspend the granting of the 3G licences, claiming the auction lacked free and fair competition as required under the constitution. The court has yet to make its ruling.
Under the terms of the auction, the NBTC must grant the licences within 90 days of approving the bid outcome.