MANILA, Philippines - Makati Mayor Jejomar Binay, the leading vice-presidential candidate, said Saturday that he has started his own investigation to uncover the identity of alleged poll fraud whistleblower "koala bear" and identify the people behind him.

"Like any citizen of the Philippines concerned din naman ako diyan," Binay told reporters at a weekly press briefing in Sulu Hotel in Quezon City.

He said he has been asking around and checking with some people who might have an idea about the supposed whistleblower's identity.

Makati City Rep. Teodoro "Teddy" Locsin Jr. on Friday claimed that people in Malacañang were behind the said witness.

Locsin said "koala bear" was released to discredit the Commission on Elections (Comelec) and the success of the automated elections.

He threatened to name the people behind the whistleblower if Malacañang would insist to stop his committee's inquiry into poll fraud allegations made by several losing congressmen.

The whistleblower, who initially used the alias Robin, told his story in a 30-minute video, wearing a straw hat and a mask that made him look like a koala bear.

The witness claimed he was part of a group that used "player" Precinct Count Optical Scan (PCOS) machines that transmitted pre-programmed election results to the receiving servers of the Comelec.

He said the data transmitted by legitimate PCOS machines were "boxed out" by data transmitted by their player PCOS machines.

The supposed witness said they approached several candidates, and Binay accepted their offer. He said they agreed to provide Binay with 7 million votes for P1.5 billion.

He added that as a bonus, they asked Binay to pick a presidential candidate that he would want to benefit from the operations. He said the Makati City mayor chose leading presidential candidate Sen. Benigno "Noynoy" Aquino III.

Binay said he knows who is behind the whistleblower, but declined to name the person. He even joked that the person behind alias Robin could be "Batman".

During the same press briefing, losing senatorial candidate Francisco "Kit" Tatad said he does not believe the claims made by the whistleblower.

"Personally, I wouldn't buy it," Tatad said, adding that despite his limited knowledge in the automated election system, he does not believe that the system can be easily manipulated to carry out massive cheating.

Sen. Aquilino Pimentel Jr. agreed with Tatad, saying that automated cheating could not be done at a very large scale. - Report from Ryan Chua, ABS-CBN News