MANILA, Philippines (AP) — The impeachment trial of the chief justice of the Philippine Supreme Court began Monday, with proceedings to focus on accusations of corruption and interfering in the prosecution of detained former President Gloria Macapagal Arroyo.

Senate President Juan Ponce Enrile promised his chamber would hold an impartial and fair trial for Chief Justice Renato Corona, who was impeached by the House of Representatives last month on allegations that include a bias for Arroyo. The former president has been charged with electoral fraud.

Renato Corona

Beleaguered Philippine Supreme Court Chief Justice Renato Corona Monday. Pic: AP.

President Benigno Aquino III has accused Corona of trying to block Arroyo’s prosecution and his reforms, which are aimed at battling pervasive corruption and poverty.

Corona has denied all wrongdoing and earlier declared in a speech before Supreme Court employees that he would fight to prove his innocence and defend the court’s independence.

The trial is the latest twist in a political drama pitting Aquino against Arroyo, his predecessor whom he blames for a decade of corruption scandals that eroded public trust in government and held back foreign investors.

Corona served as Arroyo’s chief of staff before she appointed him chief justice shortly before her stormy rule ended in 2010. Corona has accused Aquino, son of revered pro-democracy leaders, of acting like a dictator by maneuvering to oust him and gain a rubber stamp Supreme Court.

“I have not sinned against the president. I have not sinned against the people. I have not stolen from anyone,” he said in a speech before his supporters.

He said he was confident the Senate would exonerate him.

Rep. Niel Tupas Jr., who leads a congressional team of prosecutors against Corona, said the chief justice was impeached due to eight acts of alleged corruption and improperly issuing decisions that favored Arroyo.

A Philippine court ordered Arroyo arrested on Nov. 18 after she was charged with ordering the rigging of 2007 senatorial elections to favor her candidates. She has denied any wrongdoing and has hired a battery of lawyers to defend her.

Arroyo, 64, is detained in a government hospital while awaiting trial. She has sought treatment for a bone ailment.

The Supreme Court lifted a travel ban on her in November and she tried to leave the country. Aquino’s justice secretary, however, defied the Supreme Court order and had airport authorities stop her from leaving.

The country’s largest group of lawyers has backed Corona, accusing Aquino’s allies of improperly rushing his impeachment. Aquino’s administration was endangering democracy by undermining the independence of the judiciary, said the Integrated Bar of the Philippines.