The NBTC panel investigating alleged collusion between the Big Three telecom companies in bidding for 3G licences is expected to seek an extra 30 days to complete its task.

House of Representatives secretary-general Suwichak Nakwatcharachai, who is heading the National Broadcasting and Telecommunications Commission (NBTC) probe, said on Monday that all three wireless service providers that won 3G spectrum contracts -- Advance Info Service (AIS), Total Access Communication (Dtac) and True Move -- have been asked to clarify their bidding procedures.

Based on their testimony, the inquiry will determine whether they conspired with each other during the spectrum auction.

Mr Suwichak admitted that the collusion accusation would be difficult to prove.  

It was unlikely that the investigation would be completed by Nov 25, as originally announced by NBTC secretary-general Thakorn Tantasit, given that there are many people and documents involved.

“It is impossible to speed up the investigation as all panel members are overloaded with their own duties," he said, adding "We may have to ask for a 30 days extension.”

Mr Suwichal said about 30 people from the three companies have still to be questioned.

He asked anyone who has information regarding possible collusion, or can show that the telecom executives contacted each other before the auction, to come forward.