NACC secretary-general Sansern Poljiak said the commission, which is handling the investigation itself to expedite charges against wrongdoers, would convene this week to discuss its approach to the probe and invite witnesses to give testimony.

The NACC last week announced an official investigation into the case after finding grounds to proceed with the case.

Twenty-six people, including the former ministers and top executives of THAI, have been linked to the scandal and will be invited to testify before the NACC.

From 2004-05, THAI, under the supervision of the Transport Ministry and the flag-carrier’s board of directors, placed orders for six Boeing 777-200ER jets and one Airbus A340-500/600 equipped with Rolls-Royce engines.

The multibillion-baht deal was the third major order placed by THAI in connection with alleged bribes paid by Rolls-Royce to win favour for its aircraft engines. The first and second deals took place during 1991-92 and 1992-97.

Altogether, about Bt1.2 billion in alleged bribes was paid to the Thai government and airline officials for the three major deals from 1991 to 2005, according to evidence from the UK’s Serious Fraud Office.

However, the NACC said the statute of limitations had expired for cases which took place between 1991 and 1997, so it could not pursue criminal action against alleged wrongdoers.

It is now also examining evidence to decide whether or not a sub-panel should be set up to investigate another deal concerning PTT Plc, Sansern said.