Manila: A smiling ex-Philippine president Gloria Arroyo pleaded not guilty on Thursday to rigging an election, denouncing the charge that could see her jailed for life as part a vilification campaign against her.

Arroyo is accused of conspiring with a feared political warlord to rig the 2007 senatorial elections, one of many corrupt acts her successor, Benigno Aquino, alleges she committed during her near-decade in power.

"Not guilty," Arroyo, 64, told the judge after standing up in a tiny Manila courthouse wearing a neck brace to support her spine that she says is weakened from a rare disease.

Arroyo smiled and waved to a crowd of journalists after she arrived at the court from a military hospital where she had been detained for nearly three months.

She smiled repeatedly again after the brief arraignment hearing ended and headed back into a police vehicle for the return trip to hospital, then issued a statement insisting that Aquino was unfairly harassing her.

"Despite the continuous and massive vilification campaign against me and my family, I have always said that I will dispute all charges in the proper forum," Arroyo said.
"I am submitting myself to this process not only to clear my name but also as part of my commitment to respect and abide by the rules and orders of our courts."

Prosecutors allege Arroyo ordered that ballots in 2007 elections be switched in the southern province of Maguindanao so that one of her allies won the final position available in the nation's Senate.

Arroyo is alleged to have conspired with then-Maguindanao governor and close political ally Andal Ampatuan Snr to tamper with the ballots.

Ampatuan Snr, who had a reputation as a ruthless political warlord, is a co-defendant in the vote-rigging case.

He is also facing multiple murder charges for allegedly organising with his relatives the massacre in 2009 of 57 people in Maguindanao to stop a rival's election challenge, an event that forced Arroyo to end their alliance.

Aquino, the son of democracy heroes, won a landslide election victory in 2010 on a vow to fight corruption that has plagued Philippine society for decades but he said worsened dramatically during Arroyo's reign.

Arroyo has been the top target of his anti-graft campaign.

She was hit in December with a second criminal charge in relation to a $330-million telecom deal with a Chinese firm, in which her husband and a political ally allegedly received kickbacks.

Three weeks after Arroyo's arrest for alleged vote-rigging, Aquino's allies in the lower house of parliament also impeached Supreme Court chief justice Renato Corona on charges of corruption and protecting the ex-president.

The Senate is now conducting a lengthy trial to determine if the impeachment was valid and whether Corona, appointed by Arroyo just before she stepped down in 2010, should be sacked.

In a speech on Tuesday, Aquino warned his anti-corruption efforts hinged on successful prosecutions of Arroyo and Corona.

"We want to send a stern yet simple message: justice evades no one. There are no exceptions in our campaign against corruption," he said.

Arroyo was arrested at an exclusive hospital in November shortly after immigration authorities stopped her at Manila's airport from leaving the country.

Arroyo's lawyer said then her spinal disease was life-threatening, and the Supreme Court under Corona issued an order saying she was allowed to leave the country for treatment.

But Aquino insisted Arroyo was trying flee to evade prosecution and that she was not allowed to leave.

Arroyo, who is now a congresswoman after winning a parliamentary seat in the 2010 elections, was transferred to the military hospital shortly after her arrest.

No date has been set for Arroyo's trial, which could take years to complete. Arroyo applied to spend the intervening time under house arrest, but the government denied her request.