Jakarta  - An alleged high-level conspiracy to undermine Indonesia's much-respected anti-corruption commission has raised questions about the determination of President Susilo Bambang Yudhoyono to combat endemic graft.

Yudhoyono's second five-year term got off to a rough start last month after transcripts of wiretapped recordings revealed an apparent plot to frame two deputies of the Corruption Eradication Commission.

Two commission deputy chairmen, Chandra Hamzah and Bibit Samad Riyanto, were arrested last week for alleged abuse of power and extortion but were released hours after the recordings were played Wednesday at a court hearing televised nationwide.

The commission, which was set up in 2003 to fight corruption in one of the world's most graft-prone nations and has the power to arrest and prosecute, has been widely praised by the public for a series of successful prosecutions of high-profile offenders.

Legislators, governors, former ministers, businessmen, one prosecutor and top central bank officials, including an in-law of Yudhoyono, have been jailed by a special corruption court.

Allegations of attempts to muzzle the commission surfaced this year after the government drafted a bill on the corruption court, which activists said would curtail the powers of the commission, and Yudhoyono hinted that it had become too powerful.

Yudhoyono's apparent reluctance to defend the commission and its arrested deputies has prompted some activists to accuse him of complicity.

"This is a very sensitive issue," said Sunny Tanuwidjaja, a political analyst with the Center for Strategic and International Studies in Jakarta.

"The president's handling of the situation will be crucial to his future," he said. "He is seen as being too cautious, and this is unacceptable to the public."

In the wiretapped phone conversations, a person believed to be the brother of businessman Anggoro Widjoyo discussed ways to save Anggoro from prosecution with a senior state prosecutor and police investigators.

The alleged plotters also discussed evidence of bribery that could be used against commission officials investigating the businessman and spoke of cash and gifts for senior officials supporting the effort.

Yudhoyono on Sunday set up an independent panel to find the truth about the alleged plot after one of the people on the recordings spoke of presidential consent to the apparent move to frame the two commissioners.

The scandal has transfixed Indonesians. Hundreds of people on Monday took to the streets in Jakarta and more than 700,000 people have joined a Facebook page in support of the commissioners.

"The case is the tip of the iceberg of injustice in this country," a group of activists and non-governmental organizations said in a joint statement.

"If the president fails to promptly resolve the issue, we are worried that democracy will be threatened and justice will be even more elusive to the people," the statement said.

Members of the presidential investigative panel threatened to resign Wednesday after police said they had no evidence to detain the businessman's brother, Anggodo Widjaja.

They also said their recommendations that Deputy Attorney General Abdul Hakim Ritonga and Sisno Duadji, the police's national chief of criminal investigations, be sacked for suspected involvement in the conspiracy had been ignored.

Under mounting public pressure, Ritonga and Duadji tendered their resignations Thursday and national police chief Bambang Hendarso Danuri said Anggodo would remain in detention after being picked up by police Tuesday.

Tanuwidjaja said Yudhoyono's resounding victory in July's election on pledges to root out corruption and improve the economy meant that people had great expectations of him.

"Everything he does will be scrutinized," he said. "It's supposed to be a honeymoon period for him, but this case is a heavy political burden."

The commission's trouble began in May when its chairman, Antasari Azhar, was arrested for allegedly orchestrating a murder.

Azhar, who claims the charges against him were trumped up, is now on trial and could face the death penalty if convicted. (dpa)