MANILA, Philippines - Malacanang on Thursday defended President Benigno "Noynoy" Aquino III 's decision appointing former Chief Justice Hilario Davide as head of a truth commission that will investigate corruption scandals allegedly committed by former President Arroyo and other officials.

In a press conference, Presidential spokesman Edwin Lacierda said Davide's integrity and impartiality will ensure that the investigation is not a witch-hunt.

"It is not a witch-hunt. It will not be an act of vengeance on his part. It is meant to bring closure to the scandals that have happened in the past," Lacierda said in describing the commission.

The spokesman said the mandate of the commission is to gather all evidence on the alleged corruption scandals, which will be used to build an airtight case against government officials.

Aquino, one of Arroyo's fiercest critics, earlier said the truth commission would look into "any and all" controversies surrounding the departing president.

He specifically named three issues, the first being allegations she rigged the 2004 elections.

He said the commission would also look into a 329-million-dollar Internet broadband deal with a Chinese company that was eventually derailed following accusations Arroyo's allies had illegally profited from the planned contract.

He also said it would probe the alleged misuse by Arroyo's political allies of a 728-million-peso (15.68-million-dollar) government fertiliser fund.

On Wednesday, former president Joseph Estrada said he felt Davide was the wrong choice to head the truth commission tasked to investigate Arroyo and her allies for supposed crimes.

"Palagay ko yung mamumuno sa Truth Commission di bagay, yung dating CJ Davide. Eh inappoint ni GMA yun ambassador sa US. May utang na loob yan kay GMA. Paano ko... eh di abswelto yan. Kasama yan sa sabwatan sa pag-alis sa kin," he said.

For his part, the dean of the University of the Philippines College of Law said the government must make the mandate of the truth commission clear from the outset.

"Is this prosecutorial and punitive in nature or is this more of satisfying the people's clamor to know the truth and true stories behind alleged anomalous Arroyo government transactions and misgivings?" Dean Marvic Leonen said.

Leonen said healing should be part of the equation and intent, thus government might reconsider use of other configurations of punitive aspect by possibly asking for sufficient concessions from Mrs. Arroyo instead of going all out in thirst of blood.

He said the concessions may include a public admission of fault, serving community time or limited jail time, return of wealth, and others as deemed acceptable by commission.

Leonen also said Davide must not be prejudged for bias for being part of the "illegitimacy equation" that helped catapult Arroyo to power in 2001. Davide, who was Chief Justice at the time, swore in Arroyo as president after then president Estrada was ousted in a bloodless revolt.

Leonen said Davide should be judged for his future actions as head of the truth commission.