The Democrat Party yesterday criticised the Office of the Attorney-General (OAG) for failing to get to the bottom of the CTX bomb scanner corruption investigation and discovering why the direct purchase of the Suvarnabhumi Airport machines was still as expensive as buying them through a dealer.

Democrat MP and party executive Kiat Sittheeamorn said it was not right for the OAG to claim that a document from the US Justice Department incriminated no Thai politicians or officials in taking kickbacks in the purchase of the scanners. He said the document held by the OAG was the same as that received by the Democrats in the middle of last year.

The confessions of people involved, as shown in the document, indicate that it is possible that money from the price differential was given to a Thai official.

Kiat said public prosecutors should not get confused with the investigation because there are many apparent irregularities. For instance, after the contract was scrapped, the business consultant, Patriot, was allowed to use the money from the price differential, and the letter of credit involved in the purchase was not cancelled.

"If prosecutors can't explain why these things happened, they should let the Department of Special Investigation take over the case," he said.

A spokesman for the Office of the Attorney-General, Attapol Yaisawang, yesterday denied allegations that the agency was covering up the findings of US investigators.

He said the US authorities had asked the OAG to comply with the terms of a treaty between the two countries and to disclose the information they had supplied only for the purposes outlined in a request from the Royal Thai Police and the Anti-Money Laundering Office.

"The OAG has always upheld justice and done its duty in a straightforward manner," he said. "We do not protect the interests of politicians, only those of the country."

Although the information received so far from the US does not incriminate any Thai politicians or officials in taking kickbacks, the OAG will see whether the US has given all the information that was requested, and if not, it will seek further detailed answers, he said.

"If necessary, the OAG may have to question witnesses from the US to seek more evidence to pursue criminal actions," Attapol said.

He said the US authorities have not refused to let Thai prosecutors question witnesses in the US, but they have pointed out that the witnesses Thai prosecutors want to question have not been indicted of any offence.

Attapol said the OAG has asked US authorities for a list of Thai and US officials from the private and public sectors believed to have been involved in the scandal.

It has also requested a copy of the judicial writ from the case filed by the US Securities and Exchange Commission against GE InVision, as well as the verdict in the case issued by the US district court.

The OAG has not yet summoned any Thai officials or politicians for questioning in the  investigation.