MANILA » Tens of thousands of Filipinos protested in Manila on Monday (Sunday in Hawaii), outraged over accusations that an estimated $141 million in public money had been diverted into the coffers of politicians and their associates.

The peaceful four-hour rally was fueled in part by photographs posted on social media sites by the daughter of one of the suspects in the case, showing an extravagance that earned the young woman the title “the new Imelda,” after the free-spending wife of the longtime dictator Ferdinand Marcos.

President Benigno S. Aquino III, the fifth president since Marcos, has made fighting corruption a hallmark of his three-year-old administration and has received accolades from international organizations for improving government accountability. But scandals have persisted over extrajudicial killings by the police, sexual harassment by diplomats, and extortion and bribery within government agencies.

The one that drove protesters into the streets Monday involved accusations in a government audit that members of Congress worked with associates to divert discretionary public funds to sham organizations and questionable projects in return for bribes.

The National Bureau of Investigation has issued an arrest warrant for a Manila businesswoman, Janet Lim-Napoles, who is suspected of having facilitated some of the corrupt transactions with lawmakers. Her passport has been revoked, and she is the subject of a nationwide search.

Lim-Napoles denied the accusations in news media interviews conducted before the warrant was issued, but public anger grew with the circulation of the photographs showing the lavish living of her daughter, Jeane Lim-Napoles.

The younger woman, a 23-year-old fashion school graduate, sprinkled her Facebook, Twitter and other social media pages with photographs and videos of herself on vacation in London, Los Angeles and Paris. Other photos cataloged her luxury shoe collection and showed her sitting atop a Porsche, while a video of her 21st birthday party, held at a hotel in Beverly Hills, Calif., showed rows of expensive liquor and tables of sushi.

She was also photographed with Justin Bieber and Justin Timberlake at the MTV Movie Awards.

There have been a series of corruption cases involving a variety of government agencies this year.

In March, Sungjun Park, a fugitive hiding in the Philippines who was wanted in his native South Korea in connection with an investment scheme, casually left the Philippines via the Manila airport.

Rather than capturing him, Philippine government agents assisted him in avoiding detection while immigration officers used their cellphones and looked the other way. The scene was captured by airport video cameras and broadcast nationwide in the Philippines.

On July 23, the chief of the Philippine National Police announced that 14 officers were being detained in connection with the July 15 killing of two high-profile criminal suspects in their custody. There was speculation that the men were killed because they were going to reveal the names of corrupt police officers.

While those officers were in detention, several detectives in an unrelated case were placed under investigation by the Department of Justice after witnesses claimed they stole cash and drugs from an underworld leader they had arrested.

In another case, labor officials have been accused of sexually harassing Filipino women working in the Middle East who were seeking shelter at Philippine embassies. On Aug. 15, one woman told a Senate committee that she had been raped by her employer in Saudi Arabia and that when she sought help at the Philippine Embassy, an official asked her whether she had enjoyed it.

Despite the scandals, Aquino has received praise from the World Bank, financial rating agencies and others for his efforts to combat the country’s persistent corruption. He has pursued an anti-corruption campaign that seeks to monitor more closely how public money is used, while at the same time aggressively investigating and prosecuting corrupt officials.

In 2011, corruption charges were filed against his predecessor as president, Gloria Macapagal Arroyo. That same year, the chief justice of the Supreme Court — who was appointed by Arroyo — was impeached amid accusations that he had hidden wealth. The accusations of corrupt government programs have been bolstered by an exhaustive report by the Aquino administration’s auditing agency.

The latest Global Corruption Barometer report, produced by the anti-corruption group Transparency International and released in July, found that 38 percent of Filipinos perceived corruption as having decreased significantly in the past two years. That is an improvement from 6 percent in 2010 and 2011. Of the 107 countries involved in the survey, the Philippines was one of 11 where respondents reported an improving situation.

The report also said that although the Aquino administration could point to some high-profile successes, it had not been as effective in changing the institutions of government.

Vincent Lazatin, executive director of the Transparency and Accountability Network, an anti-corruption group, said that high-profile convictions did little to stop the rampant bribery and extortion within Philippine government agencies, including the Bureau of Customs, the Bureau of Internal Revenue and the police.

“There hasn’t been a trickle-down effect on everyday corruption,” he said. “The corrupt cop on the street, the corrupt customs official. They haven’t changed.”

Clearly exasperated by the recent scandals, Aquino has responded in part by excoriating members of his administration.

In his July 22 State of the Nation address, Aquino surprised many by shaming government agencies and officials, at one point citing multiple episodes in which the police had apparently executed criminals in their custody.

“Whoever masterminded all of this, prepare yourself,” he said. “I am close to learning who you are.”

Aquino pointed to the Bureau of Customs as one of the most corrupt government agencies, asserting that its officials take bribes to allow guns and drugs to be smuggled into the country.

“One can almost hear these public officials say, ‘I don’t care if the weapons go to criminal elements; I don’t care how many lives are ruined by drugs; I don’t care if our fields remain barren forever,’ ” Aquino said. “ ‘What matters is that I am rich.’ It’s every man for himself.”

For the Bureau of Immigration, Aquino appeared to express humiliation as much as anger over the escape of Park, the Korean fugitive.

“He is wanted in Korea, and their government asked for our assistance in securing his arrest,” Aquino said, addressing the senior immigration officials in the audience. “How can we face them now, when our own government employees are the ones who enabled his escape?”

His rebuke caused senior officials to offer their resignations, and some departments were reorganized. In addition, Aquino’s spokesman said Friday that the president was advocating the restructuring of the scandal-plagued program that led to the protest Monday.

Lazatin said Aquino faced an uphill battle in trying to fix government institutions that had retained corrupt practices through decades of different presidencies.

“Corruption in these government institutions is well entrenched,” Lazatin said. “Short of burning down these agencies, there is little that can be done.”