The Election Commission (EC) is investigating the leaking of personal data belonging to more than 20,000 applicants for the Senate election.
EC secretary-general Sawaeng Boonmee said that the data was leaked in file formats soon after the district-level voting in the Senate election on June 9.
"The data was leaked from an agency that put it into the system. We are working with the National Cyber Security Agency [NCSA] to prevent further data breaches leaking confidential information of applicants," he said.
"We are also investigating an agency where some officials may have leaked the data. The name of the agency will not be disclosed because the agency itself may have known nothing about the leaks.
"Moreover, the agency cooperated with and supported the EC in the district-level Senate election," Mr Sawaeng said.
Air Vice Marshal Amorn Chomchoey, the NCSA's secretary-general, said his agency and the EC have already put in place measures to prevent a database of applicants' personal information from being hacked into since the general election last year.
The NCSA and the EC will have to investigate if the leaks were committed by some officials within the agency, he said.
On Wednesday, two Senate election applicants, Kengkaj Kupakrapinyo and Wanna Horkanya, filed a complaint with the EC, asking it to investigate leaks of personal data of applicants who won in the district-level vote in the Senate election.
Mr Wanna said that shortly after voting ended, the personal data of more than 23,000 applicants, including the 13-digit number of their ID cards, was leaked and spread on chat groups on the Line application.
This was in violation of the Personal Data Protection Act, Mr Wanna said, adding that the data was stored in Excel file format, which all candidates in the district-level vote could access.
If the personal data falls into the hands of criminals, this will cause damage to the applicants, he said, adding that he also asked the Office of the Personal Data Protection Commission (PDPC) under the Ministry of Digital Economy and Society to look into the matter.
The PDPC posted on Facebook on Thursday that it has asked the EC to explain the issue and urged anyone who had received leaked data to stop sharing it.
The office will monitor any data breach and improve measures to protect personal information, the PDPC wrote.
Meanwhile, Mr Sawaeng said yesterday the EC has not prepared any contingency plan for problems that may arise after the Constitutional Court rules on the legality of four controversial provisions in the organic law governing the Senate election process next Tuesday.
"We will have to wait and see and decide what to do next after the court's ruling," Mr Sawaeng said.
At the centre of the controversy are Sections 36, 40(3), 41(3) and 42(3) of the Senate election law. Section 36 involves the self-introduction of the candidates, while the other three deal with voting -- both in the same group and across professional groups -- at the district, provincial and national levels.
The Constitutional Court said that it had enough information to make a ruling next Tuesday.
The EC is expected to continue with the provincial-level voting for the Senate election on Sunday, in which 23,645 aspirants will be whittled down to about 3,000 for the final vote.
On June 5, the court accepted for consideration petitions filed by Senate election candidates asking it to rule on the legality of the four provisions.
However, the court did not issue any injunction, finding it did not foresee any serious repercussions from the Senate poll proceeding.
The court added the EC, which is responsible for holding the election, is empowered to intervene to prevent any problems.