Senator Jose Estrada, son of former president and Manila Mayor JosephEstrada, did not enter a plea to the charge of plunder, a non-bailable offence punishable by life imprisonment.
The Sandiganbayan anti-graft court entered a not-guilty plea for him.
Estrada, who has been detained since he surrendered on June 23, told the court he has a pending petition before the Supreme Court questioning the charges, accusing the ombudsman of committing “grave abuse of discretion”.
Three senators are implicated in the multimillion-dollar scam that triggered public outrage and street protests last year. The court cases have become a test for President Benigno Aquino's anti-corruption agenda.
Senator Ramon Revilla, the first to be detained by police, was arraigned on Friday. He also refused to enter a plea, prompting the court to enter a not-guilty plea. The court was still deliberating on the charges against Senator Juan Ponce Enrile, a 90-year-old former defence minister, and has not yet issued an arrest warrant against him.
According to a government audit, at least 10 billion pesos (Bt7.3 billion) from the congressional development fund were funnelled to non-existent projects and foundations from 2007-09.
The three senators and their aides are accused of receiving a total of more than US$13 million (Bt413 million) in kickbacks from the alleged mastermind, businesswoman Janet Lim Napoles, who pleaded not guilty to charges of plunder.